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postgresql/contrib/postgres_fdw/deparse.c
Tom Lane 215824f918 In postgres_fdw, don't try to ship MULTIEXPR updates to remote server. 
In a statement like "UPDATE remote_tab SET (x,y) = (SELECT ...)",
we'd conclude that the statement could be directly executed remotely,
because the sub-SELECT is in a resjunk tlist item that's not examined
for shippability.  Currently that ends up crashing if the sub-SELECT
contains any remote Vars.  Prevent the crash by deeming MULTIEXEC
Params to be unshippable.

This is a bit of a brute-force solution, since if the sub-SELECT
*doesn't* contain any remote Vars, the current execution technology
would work; but that's not a terribly common use-case for this syntax,
I think.  In any case, we generally don't try to ship sub-SELECTs, so
it won't surprise anybody that this doesn't end up as a remote direct
update.  I'd be inclined to see if that general limitation can be fixed
before worrying about this case further.

Per report from Lukáš Sobotka.

Back-patch to 9.6.  9.5 had MULTIEXPR, but we didn't try to perform
remote direct updates then, so the case didn't arise anyway.

Discussion: https://postgr.es/m/CAJif3k+iA_ekBB5Zw2hDBaE1wtiQa4LH4_JUXrrMGwTrH0J01Q@mail.gmail.com
2020-01-26 14:31:08 -05:00

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/*-------------------------------------------------------------------------
*
* deparse.c
* Query deparser for postgres_fdw
*
* This file includes functions that examine query WHERE clauses to see
* whether they're safe to send to the remote server for execution, as
* well as functions to construct the query text to be sent. The latter
* functionality is annoyingly duplicative of ruleutils.c, but there are
* enough special considerations that it seems best to keep this separate.
* One saving grace is that we only need deparse logic for node types that
* we consider safe to send.
*
* We assume that the remote session's search_path is exactly "pg_catalog",
* and thus we need schema-qualify all and only names outside pg_catalog.
*
* We do not consider that it is ever safe to send COLLATE expressions to
* the remote server: it might not have the same collation names we do.
* (Later we might consider it safe to send COLLATE "C", but even that would
* fail on old remote servers.) An expression is considered safe to send
* only if all operator/function input collations used in it are traceable to
* Var(s) of the foreign table. That implies that if the remote server gets
* a different answer than we do, the foreign table's columns are not marked
* with collations that match the remote table's columns, which we can
* consider to be user error.
*
* Portions Copyright (c) 2012-2020, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/deparse.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/plannodes.h"
#include "optimizer/optimizer.h"
#include "optimizer/prep.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "postgres_fdw.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
/*
* Global context for foreign_expr_walker's search of an expression tree.
*/
typedef struct foreign_glob_cxt
{
PlannerInfo *root; /* global planner state */
RelOptInfo *foreignrel; /* the foreign relation we are planning for */
Relids relids; /* relids of base relations in the underlying
* scan */
} foreign_glob_cxt;
/*
* Local (per-tree-level) context for foreign_expr_walker's search.
* This is concerned with identifying collations used in the expression.
*/
typedef enum
{
FDW_COLLATE_NONE, /* expression is of a noncollatable type, or
* it has default collation that is not
* traceable to a foreign Var */
FDW_COLLATE_SAFE, /* collation derives from a foreign Var */
FDW_COLLATE_UNSAFE /* collation is non-default and derives from
* something other than a foreign Var */
} FDWCollateState;
typedef struct foreign_loc_cxt
{
Oid collation; /* OID of current collation, if any */
FDWCollateState state; /* state of current collation choice */
} foreign_loc_cxt;
/*
* Context for deparseExpr
*/
typedef struct deparse_expr_cxt
{
PlannerInfo *root; /* global planner state */
RelOptInfo *foreignrel; /* the foreign relation we are planning for */
RelOptInfo *scanrel; /* the underlying scan relation. Same as
* foreignrel, when that represents a join or
* a base relation. */
StringInfo buf; /* output buffer to append to */
List **params_list; /* exprs that will become remote Params */
} deparse_expr_cxt;
#define REL_ALIAS_PREFIX "r"
/* Handy macro to add relation name qualification */
#define ADD_REL_QUALIFIER(buf, varno) \
appendStringInfo((buf), "%s%d.", REL_ALIAS_PREFIX, (varno))
#define SUBQUERY_REL_ALIAS_PREFIX "s"
#define SUBQUERY_COL_ALIAS_PREFIX "c"
/*
* Functions to determine whether an expression can be evaluated safely on
* remote server.
*/
static bool foreign_expr_walker(Node *node,
foreign_glob_cxt *glob_cxt,
foreign_loc_cxt *outer_cxt);
static char *deparse_type_name(Oid type_oid, int32 typemod);
/*
* Functions to construct string representation of a node tree.
*/
static void deparseTargetList(StringInfo buf,
RangeTblEntry *rte,
Index rtindex,
Relation rel,
bool is_returning,
Bitmapset *attrs_used,
bool qualify_col,
List **retrieved_attrs);
static void deparseExplicitTargetList(List *tlist,
bool is_returning,
List **retrieved_attrs,
deparse_expr_cxt *context);
static void deparseSubqueryTargetList(deparse_expr_cxt *context);
static void deparseReturningList(StringInfo buf, RangeTblEntry *rte,
Index rtindex, Relation rel,
bool trig_after_row,
List *withCheckOptionList,
List *returningList,
List **retrieved_attrs);
static void deparseColumnRef(StringInfo buf, int varno, int varattno,
RangeTblEntry *rte, bool qualify_col);
static void deparseRelation(StringInfo buf, Relation rel);
static void deparseExpr(Expr *expr, deparse_expr_cxt *context);
static void deparseVar(Var *node, deparse_expr_cxt *context);
static void deparseConst(Const *node, deparse_expr_cxt *context, int showtype);
static void deparseParam(Param *node, deparse_expr_cxt *context);
static void deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context);
static void deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context);
static void deparseOpExpr(OpExpr *node, deparse_expr_cxt *context);
static void deparseOperatorName(StringInfo buf, Form_pg_operator opform);
static void deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context);
static void deparseScalarArrayOpExpr(ScalarArrayOpExpr *node,
deparse_expr_cxt *context);
static void deparseRelabelType(RelabelType *node, deparse_expr_cxt *context);
static void deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context);
static void deparseNullTest(NullTest *node, deparse_expr_cxt *context);
static void deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context);
static void printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
deparse_expr_cxt *context);
static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
deparse_expr_cxt *context);
static void deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
deparse_expr_cxt *context);
static void deparseLockingClause(deparse_expr_cxt *context);
static void appendOrderByClause(List *pathkeys, bool has_final_sort,
deparse_expr_cxt *context);
static void appendLimitClause(deparse_expr_cxt *context);
static void appendConditions(List *exprs, deparse_expr_cxt *context);
static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, bool use_alias,
Index ignore_rel, List **ignore_conds,
List **params_list);
static void deparseFromExpr(List *quals, deparse_expr_cxt *context);
static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, bool make_subquery,
Index ignore_rel, List **ignore_conds, List **params_list);
static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
static void appendAggOrderBy(List *orderList, List *targetList,
deparse_expr_cxt *context);
static void appendFunctionName(Oid funcid, deparse_expr_cxt *context);
static Node *deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
deparse_expr_cxt *context);
/*
* Helper functions
*/
static bool is_subquery_var(Var *node, RelOptInfo *foreignrel,
int *relno, int *colno);
static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
int *relno, int *colno);
/*
* Examine each qual clause in input_conds, and classify them into two groups,
* which are returned as two lists:
* - remote_conds contains expressions that can be evaluated remotely
* - local_conds contains expressions that can't be evaluated remotely
*/
void
classifyConditions(PlannerInfo *root,
RelOptInfo *baserel,
List *input_conds,
List **remote_conds,
List **local_conds)
{
ListCell *lc;
*remote_conds = NIL;
*local_conds = NIL;
foreach(lc, input_conds)
{
RestrictInfo *ri = lfirst_node(RestrictInfo, lc);
if (is_foreign_expr(root, baserel, ri->clause))
*remote_conds = lappend(*remote_conds, ri);
else
*local_conds = lappend(*local_conds, ri);
}
}
/*
* Returns true if given expr is safe to evaluate on the foreign server.
*/
bool
is_foreign_expr(PlannerInfo *root,
RelOptInfo *baserel,
Expr *expr)
{
foreign_glob_cxt glob_cxt;
foreign_loc_cxt loc_cxt;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
/*
* Check that the expression consists of nodes that are safe to execute
* remotely.
*/
glob_cxt.root = root;
glob_cxt.foreignrel = baserel;
/*
* For an upper relation, use relids from its underneath scan relation,
* because the upperrel's own relids currently aren't set to anything
* meaningful by the core code. For other relation, use their own relids.
*/
if (IS_UPPER_REL(baserel))
glob_cxt.relids = fpinfo->outerrel->relids;
else
glob_cxt.relids = baserel->relids;
loc_cxt.collation = InvalidOid;
loc_cxt.state = FDW_COLLATE_NONE;
if (!foreign_expr_walker((Node *) expr, &glob_cxt, &loc_cxt))
return false;
/*
* If the expression has a valid collation that does not arise from a
* foreign var, the expression can not be sent over.
*/
if (loc_cxt.state == FDW_COLLATE_UNSAFE)
return false;
/*
* An expression which includes any mutable functions can't be sent over
* because its result is not stable. For example, sending now() remote
* side could cause confusion from clock offsets. Future versions might
* be able to make this choice with more granularity. (We check this last
* because it requires a lot of expensive catalog lookups.)
*/
if (contain_mutable_functions((Node *) expr))
return false;
/* OK to evaluate on the remote server */
return true;
}
/*
* Check if expression is safe to execute remotely, and return true if so.
*
* In addition, *outer_cxt is updated with collation information.
*
* We must check that the expression contains only node types we can deparse,
* that all types/functions/operators are safe to send (they are "shippable"),
* and that all collations used in the expression derive from Vars of the
* foreign table. Because of the latter, the logic is pretty close to
* assign_collations_walker() in parse_collate.c, though we can assume here
* that the given expression is valid. Note function mutability is not
* currently considered here.
*/
static bool
foreign_expr_walker(Node *node,
foreign_glob_cxt *glob_cxt,
foreign_loc_cxt *outer_cxt)
{
bool check_type = true;
PgFdwRelationInfo *fpinfo;
foreign_loc_cxt inner_cxt;
Oid collation;
FDWCollateState state;
/* Need do nothing for empty subexpressions */
if (node == NULL)
return true;
/* May need server info from baserel's fdw_private struct */
fpinfo = (PgFdwRelationInfo *) (glob_cxt->foreignrel->fdw_private);
/* Set up inner_cxt for possible recursion to child nodes */
inner_cxt.collation = InvalidOid;
inner_cxt.state = FDW_COLLATE_NONE;
switch (nodeTag(node))
{
case T_Var:
{
Var *var = (Var *) node;
/*
* If the Var is from the foreign table, we consider its
* collation (if any) safe to use. If it is from another
* table, we treat its collation the same way as we would a
* Param's collation, ie it's not safe for it to have a
* non-default collation.
*/
if (bms_is_member(var->varno, glob_cxt->relids) &&
var->varlevelsup == 0)
{
/* Var belongs to foreign table */
/*
* System columns other than ctid should not be sent to
* the remote, since we don't make any effort to ensure
* that local and remote values match (tableoid, in
* particular, almost certainly doesn't match).
*/
if (var->varattno < 0 &&
var->varattno != SelfItemPointerAttributeNumber)
return false;
/* Else check the collation */
collation = var->varcollid;
state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE;
}
else
{
/* Var belongs to some other table */
collation = var->varcollid;
if (collation == InvalidOid ||
collation == DEFAULT_COLLATION_OID)
{
/*
* It's noncollatable, or it's safe to combine with a
* collatable foreign Var, so set state to NONE.
*/
state = FDW_COLLATE_NONE;
}
else
{
/*
* Do not fail right away, since the Var might appear
* in a collation-insensitive context.
*/
state = FDW_COLLATE_UNSAFE;
}
}
}
break;
case T_Const:
{
Const *c = (Const *) node;
/*
* If the constant has nondefault collation, either it's of a
* non-builtin type, or it reflects folding of a CollateExpr.
* It's unsafe to send to the remote unless it's used in a
* non-collation-sensitive context.
*/
collation = c->constcollid;
if (collation == InvalidOid ||
collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_Param:
{
Param *p = (Param *) node;
/*
* If it's a MULTIEXPR Param, punt. We can't tell from here
* whether the referenced sublink/subplan contains any remote
* Vars; if it does, handling that is too complicated to
* consider supporting at present. Fortunately, MULTIEXPR
* Params are not reduced to plain PARAM_EXEC until the end of
* planning, so we can easily detect this case. (Normal
* PARAM_EXEC Params are safe to ship because their values
* come from somewhere else in the plan tree; but a MULTIEXPR
* references a sub-select elsewhere in the same targetlist,
* so we'd be on the hook to evaluate it somehow if we wanted
* to handle such cases as direct foreign updates.)
*/
if (p->paramkind == PARAM_MULTIEXPR)
return false;
/*
* Collation rule is same as for Consts and non-foreign Vars.
*/
collation = p->paramcollid;
if (collation == InvalidOid ||
collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_SubscriptingRef:
{
SubscriptingRef *sr = (SubscriptingRef *) node;
/* Assignment should not be in restrictions. */
if (sr->refassgnexpr != NULL)
return false;
/*
* Recurse to remaining subexpressions. Since the container
* subscripts must yield (noncollatable) integers, they won't
* affect the inner_cxt state.
*/
if (!foreign_expr_walker((Node *) sr->refupperindexpr,
glob_cxt, &inner_cxt))
return false;
if (!foreign_expr_walker((Node *) sr->reflowerindexpr,
glob_cxt, &inner_cxt))
return false;
if (!foreign_expr_walker((Node *) sr->refexpr,
glob_cxt, &inner_cxt))
return false;
/*
* Container subscripting should yield same collation as
* input, but for safety use same logic as for function nodes.
*/
collation = sr->refcollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_FuncExpr:
{
FuncExpr *fe = (FuncExpr *) node;
/*
* If function used by the expression is not shippable, it
* can't be sent to remote because it might have incompatible
* semantics on remote side.
*/
if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo))
return false;
/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) fe->args,
glob_cxt, &inner_cxt))
return false;
/*
* If function's input collation is not derived from a foreign
* Var, it can't be sent to remote.
*/
if (fe->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
fe->inputcollid != inner_cxt.collation)
return false;
/*
* Detect whether node is introducing a collation not derived
* from a foreign Var. (If so, we just mark it unsafe for now
* rather than immediately returning false, since the parent
* node might not care.)
*/
collation = fe->funccollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_OpExpr:
case T_DistinctExpr: /* struct-equivalent to OpExpr */
{
OpExpr *oe = (OpExpr *) node;
/*
* Similarly, only shippable operators can be sent to remote.
* (If the operator is shippable, we assume its underlying
* function is too.)
*/
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
return false;
/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) oe->args,
glob_cxt, &inner_cxt))
return false;
/*
* If operator's input collation is not derived from a foreign
* Var, it can't be sent to remote.
*/
if (oe->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
oe->inputcollid != inner_cxt.collation)
return false;
/* Result-collation handling is same as for functions */
collation = oe->opcollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_ScalarArrayOpExpr:
{
ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
/*
* Again, only shippable operators can be sent to remote.
*/
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
return false;
/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) oe->args,
glob_cxt, &inner_cxt))
return false;
/*
* If operator's input collation is not derived from a foreign
* Var, it can't be sent to remote.
*/
if (oe->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
oe->inputcollid != inner_cxt.collation)
return false;
/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
state = FDW_COLLATE_NONE;
}
break;
case T_RelabelType:
{
RelabelType *r = (RelabelType *) node;
/*
* Recurse to input subexpression.
*/
if (!foreign_expr_walker((Node *) r->arg,
glob_cxt, &inner_cxt))
return false;
/*
* RelabelType must not introduce a collation not derived from
* an input foreign Var (same logic as for a real function).
*/
collation = r->resultcollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_BoolExpr:
{
BoolExpr *b = (BoolExpr *) node;
/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) b->args,
glob_cxt, &inner_cxt))
return false;
/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
state = FDW_COLLATE_NONE;
}
break;
case T_NullTest:
{
NullTest *nt = (NullTest *) node;
/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) nt->arg,
glob_cxt, &inner_cxt))
return false;
/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
state = FDW_COLLATE_NONE;
}
break;
case T_ArrayExpr:
{
ArrayExpr *a = (ArrayExpr *) node;
/*
* Recurse to input subexpressions.
*/
if (!foreign_expr_walker((Node *) a->elements,
glob_cxt, &inner_cxt))
return false;
/*
* ArrayExpr must not introduce a collation not derived from
* an input foreign Var (same logic as for a function).
*/
collation = a->array_collid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_List:
{
List *l = (List *) node;
ListCell *lc;
/*
* Recurse to component subexpressions.
*/
foreach(lc, l)
{
if (!foreign_expr_walker((Node *) lfirst(lc),
glob_cxt, &inner_cxt))
return false;
}
/*
* When processing a list, collation state just bubbles up
* from the list elements.
*/
collation = inner_cxt.collation;
state = inner_cxt.state;
/* Don't apply exprType() to the list. */
check_type = false;
}
break;
case T_Aggref:
{
Aggref *agg = (Aggref *) node;
ListCell *lc;
/* Not safe to pushdown when not in grouping context */
if (!IS_UPPER_REL(glob_cxt->foreignrel))
return false;
/* Only non-split aggregates are pushable. */
if (agg->aggsplit != AGGSPLIT_SIMPLE)
return false;
/* As usual, it must be shippable. */
if (!is_shippable(agg->aggfnoid, ProcedureRelationId, fpinfo))
return false;
/*
* Recurse to input args. aggdirectargs, aggorder and
* aggdistinct are all present in args, so no need to check
* their shippability explicitly.
*/
foreach(lc, agg->args)
{
Node *n = (Node *) lfirst(lc);
/* If TargetEntry, extract the expression from it */
if (IsA(n, TargetEntry))
{
TargetEntry *tle = (TargetEntry *) n;
n = (Node *) tle->expr;
}
if (!foreign_expr_walker(n, glob_cxt, &inner_cxt))
return false;
}
/*
* For aggorder elements, check whether the sort operator, if
* specified, is shippable or not.
*/
if (agg->aggorder)
{
ListCell *lc;
foreach(lc, agg->aggorder)
{
SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
Oid sortcoltype;
TypeCacheEntry *typentry;
TargetEntry *tle;
tle = get_sortgroupref_tle(srt->tleSortGroupRef,
agg->args);
sortcoltype = exprType((Node *) tle->expr);
typentry = lookup_type_cache(sortcoltype,
TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
/* Check shippability of non-default sort operator. */
if (srt->sortop != typentry->lt_opr &&
srt->sortop != typentry->gt_opr &&
!is_shippable(srt->sortop, OperatorRelationId,
fpinfo))
return false;
}
}
/* Check aggregate filter */
if (!foreign_expr_walker((Node *) agg->aggfilter,
glob_cxt, &inner_cxt))
return false;
/*
* If aggregate's input collation is not derived from a
* foreign Var, it can't be sent to remote.
*/
if (agg->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
agg->inputcollid != inner_cxt.collation)
return false;
/*
* Detect whether node is introducing a collation not derived
* from a foreign Var. (If so, we just mark it unsafe for now
* rather than immediately returning false, since the parent
* node might not care.)
*/
collation = agg->aggcollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
default:
/*
* If it's anything else, assume it's unsafe. This list can be
* expanded later, but don't forget to add deparse support below.
*/
return false;
}
/*
* If result type of given expression is not shippable, it can't be sent
* to remote because it might have incompatible semantics on remote side.
*/
if (check_type && !is_shippable(exprType(node), TypeRelationId, fpinfo))
return false;
/*
* Now, merge my collation information into my parent's state.
*/
if (state > outer_cxt->state)
{
/* Override previous parent state */
outer_cxt->collation = collation;
outer_cxt->state = state;
}
else if (state == outer_cxt->state)
{
/* Merge, or detect error if there's a collation conflict */
switch (state)
{
case FDW_COLLATE_NONE:
/* Nothing + nothing is still nothing */
break;
case FDW_COLLATE_SAFE:
if (collation != outer_cxt->collation)
{
/*
* Non-default collation always beats default.
*/
if (outer_cxt->collation == DEFAULT_COLLATION_OID)
{
/* Override previous parent state */
outer_cxt->collation = collation;
}
else if (collation != DEFAULT_COLLATION_OID)
{
/*
* Conflict; show state as indeterminate. We don't
* want to "return false" right away, since parent
* node might not care about collation.
*/
outer_cxt->state = FDW_COLLATE_UNSAFE;
}
}
break;
case FDW_COLLATE_UNSAFE:
/* We're still conflicted ... */
break;
}
}
/* It looks OK */
return true;
}
/*
* Returns true if given expr is something we'd have to send the value of
* to the foreign server.
*
* This should return true when the expression is a shippable node that
* deparseExpr would add to context->params_list. Note that we don't care
* if the expression *contains* such a node, only whether one appears at top
* level. We need this to detect cases where setrefs.c would recognize a
* false match between an fdw_exprs item (which came from the params_list)
* and an entry in fdw_scan_tlist (which we're considering putting the given
* expression into).
*/
bool
is_foreign_param(PlannerInfo *root,
RelOptInfo *baserel,
Expr *expr)
{
if (expr == NULL)
return false;
switch (nodeTag(expr))
{
case T_Var:
{
/* It would have to be sent unless it's a foreign Var */
Var *var = (Var *) expr;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) (baserel->fdw_private);
Relids relids;
if (IS_UPPER_REL(baserel))
relids = fpinfo->outerrel->relids;
else
relids = baserel->relids;
if (bms_is_member(var->varno, relids) && var->varlevelsup == 0)
return false; /* foreign Var, so not a param */
else
return true; /* it'd have to be a param */
break;
}
case T_Param:
/* Params always have to be sent to the foreign server */
return true;
default:
break;
}
return false;
}
/*
* Convert type OID + typmod info into a type name we can ship to the remote
* server. Someplace else had better have verified that this type name is
* expected to be known on the remote end.
*
* This is almost just format_type_with_typemod(), except that if left to its
* own devices, that function will make schema-qualification decisions based
* on the local search_path, which is wrong. We must schema-qualify all
* type names that are not in pg_catalog. We assume here that built-in types
* are all in pg_catalog and need not be qualified; otherwise, qualify.
*/
static char *
deparse_type_name(Oid type_oid, int32 typemod)
{
bits16 flags = FORMAT_TYPE_TYPEMOD_GIVEN;
if (!is_builtin(type_oid))
flags |= FORMAT_TYPE_FORCE_QUALIFY;
return format_type_extended(type_oid, typemod, flags);
}
/*
* Build the targetlist for given relation to be deparsed as SELECT clause.
*
* The output targetlist contains the columns that need to be fetched from the
* foreign server for the given relation. If foreignrel is an upper relation,
* then the output targetlist can also contain expressions to be evaluated on
* foreign server.
*/
List *
build_tlist_to_deparse(RelOptInfo *foreignrel)
{
List *tlist = NIL;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
ListCell *lc;
/*
* For an upper relation, we have already built the target list while
* checking shippability, so just return that.
*/
if (IS_UPPER_REL(foreignrel))
return fpinfo->grouped_tlist;
/*
* We require columns specified in foreignrel->reltarget->exprs and those
* required for evaluating the local conditions.
*/
tlist = add_to_flat_tlist(tlist,
pull_var_clause((Node *) foreignrel->reltarget->exprs,
PVC_RECURSE_PLACEHOLDERS));
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
tlist = add_to_flat_tlist(tlist,
pull_var_clause((Node *) rinfo->clause,
PVC_RECURSE_PLACEHOLDERS));
}
return tlist;
}
/*
* Deparse SELECT statement for given relation into buf.
*
* tlist contains the list of desired columns to be fetched from foreign server.
* For a base relation fpinfo->attrs_used is used to construct SELECT clause,
* hence the tlist is ignored for a base relation.
*
* remote_conds is the list of conditions to be deparsed into the WHERE clause
* (or, in the case of upper relations, into the HAVING clause).
*
* If params_list is not NULL, it receives a list of Params and other-relation
* Vars used in the clauses; these values must be transmitted to the remote
* server as parameter values.
*
* If params_list is NULL, we're generating the query for EXPLAIN purposes,
* so Params and other-relation Vars should be replaced by dummy values.
*
* pathkeys is the list of pathkeys to order the result by.
*
* is_subquery is the flag to indicate whether to deparse the specified
* relation as a subquery.
*
* List of columns selected is returned in retrieved_attrs.
*/
void
deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
List *tlist, List *remote_conds, List *pathkeys,
bool has_final_sort, bool has_limit, bool is_subquery,
List **retrieved_attrs, List **params_list)
{
deparse_expr_cxt context;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
List *quals;
/*
* We handle relations for foreign tables, joins between those and upper
* relations.
*/
Assert(IS_JOIN_REL(rel) || IS_SIMPLE_REL(rel) || IS_UPPER_REL(rel));
/* Fill portions of context common to upper, join and base relation */
context.buf = buf;
context.root = root;
context.foreignrel = rel;
context.scanrel = IS_UPPER_REL(rel) ? fpinfo->outerrel : rel;
context.params_list = params_list;
/* Construct SELECT clause */
deparseSelectSql(tlist, is_subquery, retrieved_attrs, &context);
/*
* For upper relations, the WHERE clause is built from the remote
* conditions of the underlying scan relation; otherwise, we can use the
* supplied list of remote conditions directly.
*/
if (IS_UPPER_REL(rel))
{
PgFdwRelationInfo *ofpinfo;
ofpinfo = (PgFdwRelationInfo *) fpinfo->outerrel->fdw_private;
quals = ofpinfo->remote_conds;
}
else
quals = remote_conds;
/* Construct FROM and WHERE clauses */
deparseFromExpr(quals, &context);
if (IS_UPPER_REL(rel))
{
/* Append GROUP BY clause */
appendGroupByClause(tlist, &context);
/* Append HAVING clause */
if (remote_conds)
{
appendStringInfoString(buf, " HAVING ");
appendConditions(remote_conds, &context);
}
}
/* Add ORDER BY clause if we found any useful pathkeys */
if (pathkeys)
appendOrderByClause(pathkeys, has_final_sort, &context);
/* Add LIMIT clause if necessary */
if (has_limit)
appendLimitClause(&context);
/* Add any necessary FOR UPDATE/SHARE. */
deparseLockingClause(&context);
}
/*
* Construct a simple SELECT statement that retrieves desired columns
* of the specified foreign table, and append it to "buf". The output
* contains just "SELECT ... ".
*
* We also create an integer List of the columns being retrieved, which is
* returned to *retrieved_attrs, unless we deparse the specified relation
* as a subquery.
*
* tlist is the list of desired columns. is_subquery is the flag to
* indicate whether to deparse the specified relation as a subquery.
* Read prologue of deparseSelectStmtForRel() for details.
*/
static void
deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
RelOptInfo *foreignrel = context->foreignrel;
PlannerInfo *root = context->root;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
/*
* Construct SELECT list
*/
appendStringInfoString(buf, "SELECT ");
if (is_subquery)
{
/*
* For a relation that is deparsed as a subquery, emit expressions
* specified in the relation's reltarget. Note that since this is for
* the subquery, no need to care about *retrieved_attrs.
*/
deparseSubqueryTargetList(context);
}
else if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
{
/*
* For a join or upper relation the input tlist gives the list of
* columns required to be fetched from the foreign server.
*/
deparseExplicitTargetList(tlist, false, retrieved_attrs, context);
}
else
{
/*
* For a base relation fpinfo->attrs_used gives the list of columns
* required to be fetched from the foreign server.
*/
RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
/*
* Core code already has some lock on each rel being planned, so we
* can use NoLock here.
*/
Relation rel = table_open(rte->relid, NoLock);
deparseTargetList(buf, rte, foreignrel->relid, rel, false,
fpinfo->attrs_used, false, retrieved_attrs);
table_close(rel, NoLock);
}
}
/*
* Construct a FROM clause and, if needed, a WHERE clause, and append those to
* "buf".
*
* quals is the list of clauses to be included in the WHERE clause.
* (These may or may not include RestrictInfo decoration.)
*/
static void
deparseFromExpr(List *quals, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
RelOptInfo *scanrel = context->scanrel;
/* For upper relations, scanrel must be either a joinrel or a baserel */
Assert(!IS_UPPER_REL(context->foreignrel) ||
IS_JOIN_REL(scanrel) || IS_SIMPLE_REL(scanrel));
/* Construct FROM clause */
appendStringInfoString(buf, " FROM ");
deparseFromExprForRel(buf, context->root, scanrel,
(bms_membership(scanrel->relids) == BMS_MULTIPLE),
(Index) 0, NULL, context->params_list);
/* Construct WHERE clause */
if (quals != NIL)
{
appendStringInfoString(buf, " WHERE ");
appendConditions(quals, context);
}
}
/*
* Emit a target list that retrieves the columns specified in attrs_used.
* This is used for both SELECT and RETURNING targetlists; the is_returning
* parameter is true only for a RETURNING targetlist.
*
* The tlist text is appended to buf, and we also create an integer List
* of the columns being retrieved, which is returned to *retrieved_attrs.
*
* If qualify_col is true, add relation alias before the column name.
*/
static void
deparseTargetList(StringInfo buf,
RangeTblEntry *rte,
Index rtindex,
Relation rel,
bool is_returning,
Bitmapset *attrs_used,
bool qualify_col,
List **retrieved_attrs)
{
TupleDesc tupdesc = RelationGetDescr(rel);
bool have_wholerow;
bool first;
int i;
*retrieved_attrs = NIL;
/* If there's a whole-row reference, we'll need all the columns. */
have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber,
attrs_used);
first = true;
for (i = 1; i <= tupdesc->natts; i++)
{
Form_pg_attribute attr = TupleDescAttr(tupdesc, i - 1);
/* Ignore dropped attributes. */
if (attr->attisdropped)
continue;
if (have_wholerow ||
bms_is_member(i - FirstLowInvalidHeapAttributeNumber,
attrs_used))
{
if (!first)
appendStringInfoString(buf, ", ");
else if (is_returning)
appendStringInfoString(buf, " RETURNING ");
first = false;
deparseColumnRef(buf, rtindex, i, rte, qualify_col);
*retrieved_attrs = lappend_int(*retrieved_attrs, i);
}
}
/*
* Add ctid if needed. We currently don't support retrieving any other
* system columns.
*/
if (bms_is_member(SelfItemPointerAttributeNumber - FirstLowInvalidHeapAttributeNumber,
attrs_used))
{
if (!first)
appendStringInfoString(buf, ", ");
else if (is_returning)
appendStringInfoString(buf, " RETURNING ");
first = false;
if (qualify_col)
ADD_REL_QUALIFIER(buf, rtindex);
appendStringInfoString(buf, "ctid");
*retrieved_attrs = lappend_int(*retrieved_attrs,
SelfItemPointerAttributeNumber);
}
/* Don't generate bad syntax if no undropped columns */
if (first && !is_returning)
appendStringInfoString(buf, "NULL");
}
/*
* Deparse the appropriate locking clause (FOR UPDATE or FOR SHARE) for a
* given relation (context->scanrel).
*/
static void
deparseLockingClause(deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
PlannerInfo *root = context->root;
RelOptInfo *rel = context->scanrel;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
int relid = -1;
while ((relid = bms_next_member(rel->relids, relid)) >= 0)
{
/*
* Ignore relation if it appears in a lower subquery. Locking clause
* for such a relation is included in the subquery if necessary.
*/
if (bms_is_member(relid, fpinfo->lower_subquery_rels))
continue;
/*
* Add FOR UPDATE/SHARE if appropriate. We apply locking during the
* initial row fetch, rather than later on as is done for local
* tables. The extra roundtrips involved in trying to duplicate the
* local semantics exactly don't seem worthwhile (see also comments
* for RowMarkType).
*
* Note: because we actually run the query as a cursor, this assumes
* that DECLARE CURSOR ... FOR UPDATE is supported, which it isn't
* before 8.3.
*/
if (relid == root->parse->resultRelation &&
(root->parse->commandType == CMD_UPDATE ||
root->parse->commandType == CMD_DELETE))
{
/* Relation is UPDATE/DELETE target, so use FOR UPDATE */
appendStringInfoString(buf, " FOR UPDATE");
/* Add the relation alias if we are here for a join relation */
if (IS_JOIN_REL(rel))
appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid);
}
else
{
PlanRowMark *rc = get_plan_rowmark(root->rowMarks, relid);
if (rc)
{
/*
* Relation is specified as a FOR UPDATE/SHARE target, so
* handle that. (But we could also see LCS_NONE, meaning this
* isn't a target relation after all.)
*
* For now, just ignore any [NO] KEY specification, since (a)
* it's not clear what that means for a remote table that we
* don't have complete information about, and (b) it wouldn't
* work anyway on older remote servers. Likewise, we don't
* worry about NOWAIT.
*/
switch (rc->strength)
{
case LCS_NONE:
/* No locking needed */
break;
case LCS_FORKEYSHARE:
case LCS_FORSHARE:
appendStringInfoString(buf, " FOR SHARE");
break;
case LCS_FORNOKEYUPDATE:
case LCS_FORUPDATE:
appendStringInfoString(buf, " FOR UPDATE");
break;
}
/* Add the relation alias if we are here for a join relation */
if (bms_membership(rel->relids) == BMS_MULTIPLE &&
rc->strength != LCS_NONE)
appendStringInfo(buf, " OF %s%d", REL_ALIAS_PREFIX, relid);
}
}
}
}
/*
* Deparse conditions from the provided list and append them to buf.
*
* The conditions in the list are assumed to be ANDed. This function is used to
* deparse WHERE clauses, JOIN .. ON clauses and HAVING clauses.
*
* Depending on the caller, the list elements might be either RestrictInfos
* or bare clauses.
*/
static void
appendConditions(List *exprs, deparse_expr_cxt *context)
{
int nestlevel;
ListCell *lc;
bool is_first = true;
StringInfo buf = context->buf;
/* Make sure any constants in the exprs are printed portably */
nestlevel = set_transmission_modes();
foreach(lc, exprs)
{
Expr *expr = (Expr *) lfirst(lc);
/* Extract clause from RestrictInfo, if required */
if (IsA(expr, RestrictInfo))
expr = ((RestrictInfo *) expr)->clause;
/* Connect expressions with "AND" and parenthesize each condition. */
if (!is_first)
appendStringInfoString(buf, " AND ");
appendStringInfoChar(buf, '(');
deparseExpr(expr, context);
appendStringInfoChar(buf, ')');
is_first = false;
}
reset_transmission_modes(nestlevel);
}
/* Output join name for given join type */
const char *
get_jointype_name(JoinType jointype)
{
switch (jointype)
{
case JOIN_INNER:
return "INNER";
case JOIN_LEFT:
return "LEFT";
case JOIN_RIGHT:
return "RIGHT";
case JOIN_FULL:
return "FULL";
default:
/* Shouldn't come here, but protect from buggy code. */
elog(ERROR, "unsupported join type %d", jointype);
}
/* Keep compiler happy */
return NULL;
}
/*
* Deparse given targetlist and append it to context->buf.
*
* tlist is list of TargetEntry's which in turn contain Var nodes.
*
* retrieved_attrs is the list of continuously increasing integers starting
* from 1. It has same number of entries as tlist.
*
* This is used for both SELECT and RETURNING targetlists; the is_returning
* parameter is true only for a RETURNING targetlist.
*/
static void
deparseExplicitTargetList(List *tlist,
bool is_returning,
List **retrieved_attrs,
deparse_expr_cxt *context)
{
ListCell *lc;
StringInfo buf = context->buf;
int i = 0;
*retrieved_attrs = NIL;
foreach(lc, tlist)
{
TargetEntry *tle = lfirst_node(TargetEntry, lc);
if (i > 0)
appendStringInfoString(buf, ", ");
else if (is_returning)
appendStringInfoString(buf, " RETURNING ");
deparseExpr((Expr *) tle->expr, context);
*retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
i++;
}
if (i == 0 && !is_returning)
appendStringInfoString(buf, "NULL");
}
/*
* Emit expressions specified in the given relation's reltarget.
*
* This is used for deparsing the given relation as a subquery.
*/
static void
deparseSubqueryTargetList(deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
RelOptInfo *foreignrel = context->foreignrel;
bool first;
ListCell *lc;
/* Should only be called in these cases. */
Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
first = true;
foreach(lc, foreignrel->reltarget->exprs)
{
Node *node = (Node *) lfirst(lc);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseExpr((Expr *) node, context);
}
/* Don't generate bad syntax if no expressions */
if (first)
appendStringInfoString(buf, "NULL");
}
/*
* Construct FROM clause for given relation
*
* The function constructs ... JOIN ... ON ... for join relation. For a base
* relation it just returns schema-qualified tablename, with the appropriate
* alias if so requested.
*
* 'ignore_rel' is either zero or the RT index of a target relation. In the
* latter case the function constructs FROM clause of UPDATE or USING clause
* of DELETE; it deparses the join relation as if the relation never contained
* the target relation, and creates a List of conditions to be deparsed into
* the top-level WHERE clause, which is returned to *ignore_conds.
*/
static void
deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
bool use_alias, Index ignore_rel, List **ignore_conds,
List **params_list)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
if (IS_JOIN_REL(foreignrel))
{
StringInfoData join_sql_o;
StringInfoData join_sql_i;
RelOptInfo *outerrel = fpinfo->outerrel;
RelOptInfo *innerrel = fpinfo->innerrel;
bool outerrel_is_target = false;
bool innerrel_is_target = false;
if (ignore_rel > 0 && bms_is_member(ignore_rel, foreignrel->relids))
{
/*
* If this is an inner join, add joinclauses to *ignore_conds and
* set it to empty so that those can be deparsed into the WHERE
* clause. Note that since the target relation can never be
* within the nullable side of an outer join, those could safely
* be pulled up into the WHERE clause (see foreign_join_ok()).
* Note also that since the target relation is only inner-joined
* to any other relation in the query, all conditions in the join
* tree mentioning the target relation could be deparsed into the
* WHERE clause by doing this recursively.
*/
if (fpinfo->jointype == JOIN_INNER)
{
*ignore_conds = list_concat(*ignore_conds,
fpinfo->joinclauses);
fpinfo->joinclauses = NIL;
}
/*
* Check if either of the input relations is the target relation.
*/
if (outerrel->relid == ignore_rel)
outerrel_is_target = true;
else if (innerrel->relid == ignore_rel)
innerrel_is_target = true;
}
/* Deparse outer relation if not the target relation. */
if (!outerrel_is_target)
{
initStringInfo(&join_sql_o);
deparseRangeTblRef(&join_sql_o, root, outerrel,
fpinfo->make_outerrel_subquery,
ignore_rel, ignore_conds, params_list);
/*
* If inner relation is the target relation, skip deparsing it.
* Note that since the join of the target relation with any other
* relation in the query is an inner join and can never be within
* the nullable side of an outer join, the join could be
* interchanged with higher-level joins (cf. identity 1 on outer
* join reordering shown in src/backend/optimizer/README), which
* means it's safe to skip the target-relation deparsing here.
*/
if (innerrel_is_target)
{
Assert(fpinfo->jointype == JOIN_INNER);
Assert(fpinfo->joinclauses == NIL);
appendBinaryStringInfo(buf, join_sql_o.data, join_sql_o.len);
return;
}
}
/* Deparse inner relation if not the target relation. */
if (!innerrel_is_target)
{
initStringInfo(&join_sql_i);
deparseRangeTblRef(&join_sql_i, root, innerrel,
fpinfo->make_innerrel_subquery,
ignore_rel, ignore_conds, params_list);
/*
* If outer relation is the target relation, skip deparsing it.
* See the above note about safety.
*/
if (outerrel_is_target)
{
Assert(fpinfo->jointype == JOIN_INNER);
Assert(fpinfo->joinclauses == NIL);
appendBinaryStringInfo(buf, join_sql_i.data, join_sql_i.len);
return;
}
}
/* Neither of the relations is the target relation. */
Assert(!outerrel_is_target && !innerrel_is_target);
/*
* For a join relation FROM clause entry is deparsed as
*
* ((outer relation) <join type> (inner relation) ON (joinclauses))
*/
appendStringInfo(buf, "(%s %s JOIN %s ON ", join_sql_o.data,
get_jointype_name(fpinfo->jointype), join_sql_i.data);
/* Append join clause; (TRUE) if no join clause */
if (fpinfo->joinclauses)
{
deparse_expr_cxt context;
context.buf = buf;
context.foreignrel = foreignrel;
context.scanrel = foreignrel;
context.root = root;
context.params_list = params_list;
appendStringInfoChar(buf, '(');
appendConditions(fpinfo->joinclauses, &context);
appendStringInfoChar(buf, ')');
}
else
appendStringInfoString(buf, "(TRUE)");
/* End the FROM clause entry. */
appendStringInfoChar(buf, ')');
}
else
{
RangeTblEntry *rte = planner_rt_fetch(foreignrel->relid, root);
/*
* Core code already has some lock on each rel being planned, so we
* can use NoLock here.
*/
Relation rel = table_open(rte->relid, NoLock);
deparseRelation(buf, rel);
/*
* Add a unique alias to avoid any conflict in relation names due to
* pulled up subqueries in the query being built for a pushed down
* join.
*/
if (use_alias)
appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, foreignrel->relid);
table_close(rel, NoLock);
}
}
/*
* Append FROM clause entry for the given relation into buf.
*/
static void
deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
bool make_subquery, Index ignore_rel, List **ignore_conds,
List **params_list)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
/* Should only be called in these cases. */
Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
Assert(fpinfo->local_conds == NIL);
/* If make_subquery is true, deparse the relation as a subquery. */
if (make_subquery)
{
List *retrieved_attrs;
int ncols;
/*
* The given relation shouldn't contain the target relation, because
* this should only happen for input relations for a full join, and
* such relations can never contain an UPDATE/DELETE target.
*/
Assert(ignore_rel == 0 ||
!bms_is_member(ignore_rel, foreignrel->relids));
/* Deparse the subquery representing the relation. */
appendStringInfoChar(buf, '(');
deparseSelectStmtForRel(buf, root, foreignrel, NIL,
fpinfo->remote_conds, NIL,
false, false, true,
&retrieved_attrs, params_list);
appendStringInfoChar(buf, ')');
/* Append the relation alias. */
appendStringInfo(buf, " %s%d", SUBQUERY_REL_ALIAS_PREFIX,
fpinfo->relation_index);
/*
* Append the column aliases if needed. Note that the subquery emits
* expressions specified in the relation's reltarget (see
* deparseSubqueryTargetList).
*/
ncols = list_length(foreignrel->reltarget->exprs);
if (ncols > 0)
{
int i;
appendStringInfoChar(buf, '(');
for (i = 1; i <= ncols; i++)
{
if (i > 1)
appendStringInfoString(buf, ", ");
appendStringInfo(buf, "%s%d", SUBQUERY_COL_ALIAS_PREFIX, i);
}
appendStringInfoChar(buf, ')');
}
}
else
deparseFromExprForRel(buf, root, foreignrel, true, ignore_rel,
ignore_conds, params_list);
}
/*
* deparse remote INSERT statement
*
* The statement text is appended to buf, and we also create an integer List
* of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any),
* which is returned to *retrieved_attrs.
*/
void
deparseInsertSql(StringInfo buf, RangeTblEntry *rte,
Index rtindex, Relation rel,
List *targetAttrs, bool doNothing,
List *withCheckOptionList, List *returningList,
List **retrieved_attrs)
{
AttrNumber pindex;
bool first;
ListCell *lc;
appendStringInfoString(buf, "INSERT INTO ");
deparseRelation(buf, rel);
if (targetAttrs)
{
appendStringInfoChar(buf, '(');
first = true;
foreach(lc, targetAttrs)
{
int attnum = lfirst_int(lc);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, rte, false);
}
appendStringInfoString(buf, ") VALUES (");
pindex = 1;
first = true;
foreach(lc, targetAttrs)
{
if (!first)
appendStringInfoString(buf, ", ");
first = false;
appendStringInfo(buf, "$%d", pindex);
pindex++;
}
appendStringInfoChar(buf, ')');
}
else
appendStringInfoString(buf, " DEFAULT VALUES");
if (doNothing)
appendStringInfoString(buf, " ON CONFLICT DO NOTHING");
deparseReturningList(buf, rte, rtindex, rel,
rel->trigdesc && rel->trigdesc->trig_insert_after_row,
withCheckOptionList, returningList, retrieved_attrs);
}
/*
* deparse remote UPDATE statement
*
* The statement text is appended to buf, and we also create an integer List
* of the columns being retrieved by WITH CHECK OPTION or RETURNING (if any),
* which is returned to *retrieved_attrs.
*/
void
deparseUpdateSql(StringInfo buf, RangeTblEntry *rte,
Index rtindex, Relation rel,
List *targetAttrs,
List *withCheckOptionList, List *returningList,
List **retrieved_attrs)
{
AttrNumber pindex;
bool first;
ListCell *lc;
appendStringInfoString(buf, "UPDATE ");
deparseRelation(buf, rel);
appendStringInfoString(buf, " SET ");
pindex = 2; /* ctid is always the first param */
first = true;
foreach(lc, targetAttrs)
{
int attnum = lfirst_int(lc);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, rte, false);
appendStringInfo(buf, " = $%d", pindex);
pindex++;
}
appendStringInfoString(buf, " WHERE ctid = $1");
deparseReturningList(buf, rte, rtindex, rel,
rel->trigdesc && rel->trigdesc->trig_update_after_row,
withCheckOptionList, returningList, retrieved_attrs);
}
/*
* deparse remote UPDATE statement
*
* 'buf' is the output buffer to append the statement to
* 'rtindex' is the RT index of the associated target relation
* 'rel' is the relation descriptor for the target relation
* 'foreignrel' is the RelOptInfo for the target relation or the join relation
* containing all base relations in the query
* 'targetlist' is the tlist of the underlying foreign-scan plan node
* 'targetAttrs' is the target columns of the UPDATE
* 'remote_conds' is the qual clauses that must be evaluated remotely
* '*params_list' is an output list of exprs that will become remote Params
* 'returningList' is the RETURNING targetlist
* '*retrieved_attrs' is an output list of integers of columns being retrieved
* by RETURNING (if any)
*/
void
deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
RelOptInfo *foreignrel,
List *targetlist,
List *targetAttrs,
List *remote_conds,
List **params_list,
List *returningList,
List **retrieved_attrs)
{
deparse_expr_cxt context;
int nestlevel;
bool first;
ListCell *lc;
RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
/* Set up context struct for recursion */
context.root = root;
context.foreignrel = foreignrel;
context.scanrel = foreignrel;
context.buf = buf;
context.params_list = params_list;
appendStringInfoString(buf, "UPDATE ");
deparseRelation(buf, rel);
if (foreignrel->reloptkind == RELOPT_JOINREL)
appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex);
appendStringInfoString(buf, " SET ");
/* Make sure any constants in the exprs are printed portably */
nestlevel = set_transmission_modes();
first = true;
foreach(lc, targetAttrs)
{
int attnum = lfirst_int(lc);
TargetEntry *tle = get_tle_by_resno(targetlist, attnum);
if (!tle)
elog(ERROR, "attribute number %d not found in UPDATE targetlist",
attnum);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseColumnRef(buf, rtindex, attnum, rte, false);
appendStringInfoString(buf, " = ");
deparseExpr((Expr *) tle->expr, &context);
}
reset_transmission_modes(nestlevel);
if (foreignrel->reloptkind == RELOPT_JOINREL)
{
List *ignore_conds = NIL;
appendStringInfoString(buf, " FROM ");
deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
&ignore_conds, params_list);
remote_conds = list_concat(remote_conds, ignore_conds);
}
if (remote_conds)
{
appendStringInfoString(buf, " WHERE ");
appendConditions(remote_conds, &context);
}
if (foreignrel->reloptkind == RELOPT_JOINREL)
deparseExplicitTargetList(returningList, true, retrieved_attrs,
&context);
else
deparseReturningList(buf, rte, rtindex, rel, false,
NIL, returningList, retrieved_attrs);
}
/*
* deparse remote DELETE statement
*
* The statement text is appended to buf, and we also create an integer List
* of the columns being retrieved by RETURNING (if any), which is returned
* to *retrieved_attrs.
*/
void
deparseDeleteSql(StringInfo buf, RangeTblEntry *rte,
Index rtindex, Relation rel,
List *returningList,
List **retrieved_attrs)
{
appendStringInfoString(buf, "DELETE FROM ");
deparseRelation(buf, rel);
appendStringInfoString(buf, " WHERE ctid = $1");
deparseReturningList(buf, rte, rtindex, rel,
rel->trigdesc && rel->trigdesc->trig_delete_after_row,
NIL, returningList, retrieved_attrs);
}
/*
* deparse remote DELETE statement
*
* 'buf' is the output buffer to append the statement to
* 'rtindex' is the RT index of the associated target relation
* 'rel' is the relation descriptor for the target relation
* 'foreignrel' is the RelOptInfo for the target relation or the join relation
* containing all base relations in the query
* 'remote_conds' is the qual clauses that must be evaluated remotely
* '*params_list' is an output list of exprs that will become remote Params
* 'returningList' is the RETURNING targetlist
* '*retrieved_attrs' is an output list of integers of columns being retrieved
* by RETURNING (if any)
*/
void
deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
RelOptInfo *foreignrel,
List *remote_conds,
List **params_list,
List *returningList,
List **retrieved_attrs)
{
deparse_expr_cxt context;
/* Set up context struct for recursion */
context.root = root;
context.foreignrel = foreignrel;
context.scanrel = foreignrel;
context.buf = buf;
context.params_list = params_list;
appendStringInfoString(buf, "DELETE FROM ");
deparseRelation(buf, rel);
if (foreignrel->reloptkind == RELOPT_JOINREL)
appendStringInfo(buf, " %s%d", REL_ALIAS_PREFIX, rtindex);
if (foreignrel->reloptkind == RELOPT_JOINREL)
{
List *ignore_conds = NIL;
appendStringInfoString(buf, " USING ");
deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
&ignore_conds, params_list);
remote_conds = list_concat(remote_conds, ignore_conds);
}
if (remote_conds)
{
appendStringInfoString(buf, " WHERE ");
appendConditions(remote_conds, &context);
}
if (foreignrel->reloptkind == RELOPT_JOINREL)
deparseExplicitTargetList(returningList, true, retrieved_attrs,
&context);
else
deparseReturningList(buf, planner_rt_fetch(rtindex, root),
rtindex, rel, false,
NIL, returningList, retrieved_attrs);
}
/*
* Add a RETURNING clause, if needed, to an INSERT/UPDATE/DELETE.
*/
static void
deparseReturningList(StringInfo buf, RangeTblEntry *rte,
Index rtindex, Relation rel,
bool trig_after_row,
List *withCheckOptionList,
List *returningList,
List **retrieved_attrs)
{
Bitmapset *attrs_used = NULL;
if (trig_after_row)
{
/* whole-row reference acquires all non-system columns */
attrs_used =
bms_make_singleton(0 - FirstLowInvalidHeapAttributeNumber);
}
if (withCheckOptionList != NIL)
{
/*
* We need the attrs, non-system and system, mentioned in the local
* query's WITH CHECK OPTION list.
*
* Note: we do this to ensure that WCO constraints will be evaluated
* on the data actually inserted/updated on the remote side, which
* might differ from the data supplied by the core code, for example
* as a result of remote triggers.
*/
pull_varattnos((Node *) withCheckOptionList, rtindex,
&attrs_used);
}
if (returningList != NIL)
{
/*
* We need the attrs, non-system and system, mentioned in the local
* query's RETURNING list.
*/
pull_varattnos((Node *) returningList, rtindex,
&attrs_used);
}
if (attrs_used != NULL)
deparseTargetList(buf, rte, rtindex, rel, true, attrs_used, false,
retrieved_attrs);
else
*retrieved_attrs = NIL;
}
/*
* Construct SELECT statement to acquire size in blocks of given relation.
*
* Note: we use local definition of block size, not remote definition.
* This is perhaps debatable.
*
* Note: pg_relation_size() exists in 8.1 and later.
*/
void
deparseAnalyzeSizeSql(StringInfo buf, Relation rel)
{
StringInfoData relname;
/* We'll need the remote relation name as a literal. */
initStringInfo(&relname);
deparseRelation(&relname, rel);
appendStringInfoString(buf, "SELECT pg_catalog.pg_relation_size(");
deparseStringLiteral(buf, relname.data);
appendStringInfo(buf, "::pg_catalog.regclass) / %d", BLCKSZ);
}
/*
* Construct SELECT statement to acquire sample rows of given relation.
*
* SELECT command is appended to buf, and list of columns retrieved
* is returned to *retrieved_attrs.
*/
void
deparseAnalyzeSql(StringInfo buf, Relation rel, List **retrieved_attrs)
{
Oid relid = RelationGetRelid(rel);
TupleDesc tupdesc = RelationGetDescr(rel);
int i;
char *colname;
List *options;
ListCell *lc;
bool first = true;
*retrieved_attrs = NIL;
appendStringInfoString(buf, "SELECT ");
for (i = 0; i < tupdesc->natts; i++)
{
/* Ignore dropped columns. */
if (TupleDescAttr(tupdesc, i)->attisdropped)
continue;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
/* Use attribute name or column_name option. */
colname = NameStr(TupleDescAttr(tupdesc, i)->attname);
options = GetForeignColumnOptions(relid, i + 1);
foreach(lc, options)
{
DefElem *def = (DefElem *) lfirst(lc);
if (strcmp(def->defname, "column_name") == 0)
{
colname = defGetString(def);
break;
}
}
appendStringInfoString(buf, quote_identifier(colname));
*retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
}
/* Don't generate bad syntax for zero-column relation. */
if (first)
appendStringInfoString(buf, "NULL");
/*
* Construct FROM clause
*/
appendStringInfoString(buf, " FROM ");
deparseRelation(buf, rel);
}
/*
* Construct name to use for given column, and emit it into buf.
* If it has a column_name FDW option, use that instead of attribute name.
*
* If qualify_col is true, qualify column name with the alias of relation.
*/
static void
deparseColumnRef(StringInfo buf, int varno, int varattno, RangeTblEntry *rte,
bool qualify_col)
{
/* We support fetching the remote side's CTID and OID. */
if (varattno == SelfItemPointerAttributeNumber)
{
if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);
appendStringInfoString(buf, "ctid");
}
else if (varattno < 0)
{
/*
* All other system attributes are fetched as 0, except for table OID,
* which is fetched as the local table OID. However, we must be
* careful; the table could be beneath an outer join, in which case it
* must go to NULL whenever the rest of the row does.
*/
Oid fetchval = 0;
if (varattno == TableOidAttributeNumber)
fetchval = rte->relid;
if (qualify_col)
{
appendStringInfoString(buf, "CASE WHEN (");
ADD_REL_QUALIFIER(buf, varno);
appendStringInfo(buf, "*)::text IS NOT NULL THEN %u END", fetchval);
}
else
appendStringInfo(buf, "%u", fetchval);
}
else if (varattno == 0)
{
/* Whole row reference */
Relation rel;
Bitmapset *attrs_used;
/* Required only to be passed down to deparseTargetList(). */
List *retrieved_attrs;
/*
* The lock on the relation will be held by upper callers, so it's
* fine to open it with no lock here.
*/
rel = table_open(rte->relid, NoLock);
/*
* The local name of the foreign table can not be recognized by the
* foreign server and the table it references on foreign server might
* have different column ordering or different columns than those
* declared locally. Hence we have to deparse whole-row reference as
* ROW(columns referenced locally). Construct this by deparsing a
* "whole row" attribute.
*/
attrs_used = bms_add_member(NULL,
0 - FirstLowInvalidHeapAttributeNumber);
/*
* In case the whole-row reference is under an outer join then it has
* to go NULL whenever the rest of the row goes NULL. Deparsing a join
* query would always involve multiple relations, thus qualify_col
* would be true.
*/
if (qualify_col)
{
appendStringInfoString(buf, "CASE WHEN (");
ADD_REL_QUALIFIER(buf, varno);
appendStringInfoString(buf, "*)::text IS NOT NULL THEN ");
}
appendStringInfoString(buf, "ROW(");
deparseTargetList(buf, rte, varno, rel, false, attrs_used, qualify_col,
&retrieved_attrs);
appendStringInfoChar(buf, ')');
/* Complete the CASE WHEN statement started above. */
if (qualify_col)
appendStringInfoString(buf, " END");
table_close(rel, NoLock);
bms_free(attrs_used);
}
else
{
char *colname = NULL;
List *options;
ListCell *lc;
/* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */
Assert(!IS_SPECIAL_VARNO(varno));
/*
* If it's a column of a foreign table, and it has the column_name FDW
* option, use that value.
*/
options = GetForeignColumnOptions(rte->relid, varattno);
foreach(lc, options)
{
DefElem *def = (DefElem *) lfirst(lc);
if (strcmp(def->defname, "column_name") == 0)
{
colname = defGetString(def);
break;
}
}
/*
* If it's a column of a regular table or it doesn't have column_name
* FDW option, use attribute name.
*/
if (colname == NULL)
colname = get_attname(rte->relid, varattno, false);
if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);
appendStringInfoString(buf, quote_identifier(colname));
}
}
/*
* Append remote name of specified foreign table to buf.
* Use value of table_name FDW option (if any) instead of relation's name.
* Similarly, schema_name FDW option overrides schema name.
*/
static void
deparseRelation(StringInfo buf, Relation rel)
{
ForeignTable *table;
const char *nspname = NULL;
const char *relname = NULL;
ListCell *lc;
/* obtain additional catalog information. */
table = GetForeignTable(RelationGetRelid(rel));
/*
* Use value of FDW options if any, instead of the name of object itself.
*/
foreach(lc, table->options)
{
DefElem *def = (DefElem *) lfirst(lc);
if (strcmp(def->defname, "schema_name") == 0)
nspname = defGetString(def);
else if (strcmp(def->defname, "table_name") == 0)
relname = defGetString(def);
}
/*
* Note: we could skip printing the schema name if it's pg_catalog, but
* that doesn't seem worth the trouble.
*/
if (nspname == NULL)
nspname = get_namespace_name(RelationGetNamespace(rel));
if (relname == NULL)
relname = RelationGetRelationName(rel);
appendStringInfo(buf, "%s.%s",
quote_identifier(nspname), quote_identifier(relname));
}
/*
* Append a SQL string literal representing "val" to buf.
*/
void
deparseStringLiteral(StringInfo buf, const char *val)
{
const char *valptr;
/*
* Rather than making assumptions about the remote server's value of
* standard_conforming_strings, always use E'foo' syntax if there are any
* backslashes. This will fail on remote servers before 8.1, but those
* are long out of support.
*/
if (strchr(val, '\\') != NULL)
appendStringInfoChar(buf, ESCAPE_STRING_SYNTAX);
appendStringInfoChar(buf, '\'');
for (valptr = val; *valptr; valptr++)
{
char ch = *valptr;
if (SQL_STR_DOUBLE(ch, true))
appendStringInfoChar(buf, ch);
appendStringInfoChar(buf, ch);
}
appendStringInfoChar(buf, '\'');
}
/*
* Deparse given expression into context->buf.
*
* This function must support all the same node types that foreign_expr_walker
* accepts.
*
* Note: unlike ruleutils.c, we just use a simple hard-wired parenthesization
* scheme: anything more complex than a Var, Const, function call or cast
* should be self-parenthesized.
*/
static void
deparseExpr(Expr *node, deparse_expr_cxt *context)
{
if (node == NULL)
return;
switch (nodeTag(node))
{
case T_Var:
deparseVar((Var *) node, context);
break;
case T_Const:
deparseConst((Const *) node, context, 0);
break;
case T_Param:
deparseParam((Param *) node, context);
break;
case T_SubscriptingRef:
deparseSubscriptingRef((SubscriptingRef *) node, context);
break;
case T_FuncExpr:
deparseFuncExpr((FuncExpr *) node, context);
break;
case T_OpExpr:
deparseOpExpr((OpExpr *) node, context);
break;
case T_DistinctExpr:
deparseDistinctExpr((DistinctExpr *) node, context);
break;
case T_ScalarArrayOpExpr:
deparseScalarArrayOpExpr((ScalarArrayOpExpr *) node, context);
break;
case T_RelabelType:
deparseRelabelType((RelabelType *) node, context);
break;
case T_BoolExpr:
deparseBoolExpr((BoolExpr *) node, context);
break;
case T_NullTest:
deparseNullTest((NullTest *) node, context);
break;
case T_ArrayExpr:
deparseArrayExpr((ArrayExpr *) node, context);
break;
case T_Aggref:
deparseAggref((Aggref *) node, context);
break;
default:
elog(ERROR, "unsupported expression type for deparse: %d",
(int) nodeTag(node));
break;
}
}
/*
* Deparse given Var node into context->buf.
*
* If the Var belongs to the foreign relation, just print its remote name.
* Otherwise, it's effectively a Param (and will in fact be a Param at
* run time). Handle it the same way we handle plain Params --- see
* deparseParam for comments.
*/
static void
deparseVar(Var *node, deparse_expr_cxt *context)
{
Relids relids = context->scanrel->relids;
int relno;
int colno;
/* Qualify columns when multiple relations are involved. */
bool qualify_col = (bms_membership(relids) == BMS_MULTIPLE);
/*
* If the Var belongs to the foreign relation that is deparsed as a
* subquery, use the relation and column alias to the Var provided by the
* subquery, instead of the remote name.
*/
if (is_subquery_var(node, context->scanrel, &relno, &colno))
{
appendStringInfo(context->buf, "%s%d.%s%d",
SUBQUERY_REL_ALIAS_PREFIX, relno,
SUBQUERY_COL_ALIAS_PREFIX, colno);
return;
}
if (bms_is_member(node->varno, relids) && node->varlevelsup == 0)
deparseColumnRef(context->buf, node->varno, node->varattno,
planner_rt_fetch(node->varno, context->root),
qualify_col);
else
{
/* Treat like a Param */
if (context->params_list)
{
int pindex = 0;
ListCell *lc;
/* find its index in params_list */
foreach(lc, *context->params_list)
{
pindex++;
if (equal(node, (Node *) lfirst(lc)))
break;
}
if (lc == NULL)
{
/* not in list, so add it */
pindex++;
*context->params_list = lappend(*context->params_list, node);
}
printRemoteParam(pindex, node->vartype, node->vartypmod, context);
}
else
{
printRemotePlaceholder(node->vartype, node->vartypmod, context);
}
}
}
/*
* Deparse given constant value into context->buf.
*
* This function has to be kept in sync with ruleutils.c's get_const_expr.
* As for that function, showtype can be -1 to never show "::typename" decoration,
* or +1 to always show it, or 0 to show it only if the constant wouldn't be assumed
* to be the right type by default.
*/
static void
deparseConst(Const *node, deparse_expr_cxt *context, int showtype)
{
StringInfo buf = context->buf;
Oid typoutput;
bool typIsVarlena;
char *extval;
bool isfloat = false;
bool needlabel;
if (node->constisnull)
{
appendStringInfoString(buf, "NULL");
if (showtype >= 0)
appendStringInfo(buf, "::%s",
deparse_type_name(node->consttype,
node->consttypmod));
return;
}
getTypeOutputInfo(node->consttype,
&typoutput, &typIsVarlena);
extval = OidOutputFunctionCall(typoutput, node->constvalue);
switch (node->consttype)
{
case INT2OID:
case INT4OID:
case INT8OID:
case OIDOID:
case FLOAT4OID:
case FLOAT8OID:
case NUMERICOID:
{
/*
* No need to quote unless it's a special value such as 'NaN'.
* See comments in get_const_expr().
*/
if (strspn(extval, "0123456789+-eE.") == strlen(extval))
{
if (extval[0] == '+' || extval[0] == '-')
appendStringInfo(buf, "(%s)", extval);
else
appendStringInfoString(buf, extval);
if (strcspn(extval, "eE.") != strlen(extval))
isfloat = true; /* it looks like a float */
}
else
appendStringInfo(buf, "'%s'", extval);
}
break;
case BITOID:
case VARBITOID:
appendStringInfo(buf, "B'%s'", extval);
break;
case BOOLOID:
if (strcmp(extval, "t") == 0)
appendStringInfoString(buf, "true");
else
appendStringInfoString(buf, "false");
break;
default:
deparseStringLiteral(buf, extval);
break;
}
pfree(extval);
if (showtype < 0)
return;
/*
* For showtype == 0, append ::typename unless the constant will be
* implicitly typed as the right type when it is read in.
*
* XXX this code has to be kept in sync with the behavior of the parser,
* especially make_const.
*/
switch (node->consttype)
{
case BOOLOID:
case INT4OID:
case UNKNOWNOID:
needlabel = false;
break;
case NUMERICOID:
needlabel = !isfloat || (node->consttypmod >= 0);
break;
default:
needlabel = true;
break;
}
if (needlabel || showtype > 0)
appendStringInfo(buf, "::%s",
deparse_type_name(node->consttype,
node->consttypmod));
}
/*
* Deparse given Param node.
*
* If we're generating the query "for real", add the Param to
* context->params_list if it's not already present, and then use its index
* in that list as the remote parameter number. During EXPLAIN, there's
* no need to identify a parameter number.
*/
static void
deparseParam(Param *node, deparse_expr_cxt *context)
{
if (context->params_list)
{
int pindex = 0;
ListCell *lc;
/* find its index in params_list */
foreach(lc, *context->params_list)
{
pindex++;
if (equal(node, (Node *) lfirst(lc)))
break;
}
if (lc == NULL)
{
/* not in list, so add it */
pindex++;
*context->params_list = lappend(*context->params_list, node);
}
printRemoteParam(pindex, node->paramtype, node->paramtypmod, context);
}
else
{
printRemotePlaceholder(node->paramtype, node->paramtypmod, context);
}
}
/*
* Deparse a container subscript expression.
*/
static void
deparseSubscriptingRef(SubscriptingRef *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
ListCell *lowlist_item;
ListCell *uplist_item;
/* Always parenthesize the expression. */
appendStringInfoChar(buf, '(');
/*
* Deparse referenced array expression first. If that expression includes
* a cast, we have to parenthesize to prevent the array subscript from
* being taken as typename decoration. We can avoid that in the typical
* case of subscripting a Var, but otherwise do it.
*/
if (IsA(node->refexpr, Var))
deparseExpr(node->refexpr, context);
else
{
appendStringInfoChar(buf, '(');
deparseExpr(node->refexpr, context);
appendStringInfoChar(buf, ')');
}
/* Deparse subscript expressions. */
lowlist_item = list_head(node->reflowerindexpr); /* could be NULL */
foreach(uplist_item, node->refupperindexpr)
{
appendStringInfoChar(buf, '[');
if (lowlist_item)
{
deparseExpr(lfirst(lowlist_item), context);
appendStringInfoChar(buf, ':');
lowlist_item = lnext(node->reflowerindexpr, lowlist_item);
}
deparseExpr(lfirst(uplist_item), context);
appendStringInfoChar(buf, ']');
}
appendStringInfoChar(buf, ')');
}
/*
* Deparse a function call.
*/
static void
deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
bool use_variadic;
bool first;
ListCell *arg;
/*
* If the function call came from an implicit coercion, then just show the
* first argument.
*/
if (node->funcformat == COERCE_IMPLICIT_CAST)
{
deparseExpr((Expr *) linitial(node->args), context);
return;
}
/*
* If the function call came from a cast, then show the first argument
* plus an explicit cast operation.
*/
if (node->funcformat == COERCE_EXPLICIT_CAST)
{
Oid rettype = node->funcresulttype;
int32 coercedTypmod;
/* Get the typmod if this is a length-coercion function */
(void) exprIsLengthCoercion((Node *) node, &coercedTypmod);
deparseExpr((Expr *) linitial(node->args), context);
appendStringInfo(buf, "::%s",
deparse_type_name(rettype, coercedTypmod));
return;
}
/* Check if need to print VARIADIC (cf. ruleutils.c) */
use_variadic = node->funcvariadic;
/*
* Normal function: display as proname(args).
*/
appendFunctionName(node->funcid, context);
appendStringInfoChar(buf, '(');
/* ... and all the arguments */
first = true;
foreach(arg, node->args)
{
if (!first)
appendStringInfoString(buf, ", ");
if (use_variadic && lnext(node->args, arg) == NULL)
appendStringInfoString(buf, "VARIADIC ");
deparseExpr((Expr *) lfirst(arg), context);
first = false;
}
appendStringInfoChar(buf, ')');
}
/*
* Deparse given operator expression. To avoid problems around
* priority of operations, we always parenthesize the arguments.
*/
static void
deparseOpExpr(OpExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
HeapTuple tuple;
Form_pg_operator form;
char oprkind;
ListCell *arg;
/* Retrieve information about the operator from system catalog. */
tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for operator %u", node->opno);
form = (Form_pg_operator) GETSTRUCT(tuple);
oprkind = form->oprkind;
/* Sanity check. */
Assert((oprkind == 'r' && list_length(node->args) == 1) ||
(oprkind == 'l' && list_length(node->args) == 1) ||
(oprkind == 'b' && list_length(node->args) == 2));
/* Always parenthesize the expression. */
appendStringInfoChar(buf, '(');
/* Deparse left operand. */
if (oprkind == 'r' || oprkind == 'b')
{
arg = list_head(node->args);
deparseExpr(lfirst(arg), context);
appendStringInfoChar(buf, ' ');
}
/* Deparse operator name. */
deparseOperatorName(buf, form);
/* Deparse right operand. */
if (oprkind == 'l' || oprkind == 'b')
{
arg = list_tail(node->args);
appendStringInfoChar(buf, ' ');
deparseExpr(lfirst(arg), context);
}
appendStringInfoChar(buf, ')');
ReleaseSysCache(tuple);
}
/*
* Print the name of an operator.
*/
static void
deparseOperatorName(StringInfo buf, Form_pg_operator opform)
{
char *opname;
/* opname is not a SQL identifier, so we should not quote it. */
opname = NameStr(opform->oprname);
/* Print schema name only if it's not pg_catalog */
if (opform->oprnamespace != PG_CATALOG_NAMESPACE)
{
const char *opnspname;
opnspname = get_namespace_name(opform->oprnamespace);
/* Print fully qualified operator name. */
appendStringInfo(buf, "OPERATOR(%s.%s)",
quote_identifier(opnspname), opname);
}
else
{
/* Just print operator name. */
appendStringInfoString(buf, opname);
}
}
/*
* Deparse IS DISTINCT FROM.
*/
static void
deparseDistinctExpr(DistinctExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
Assert(list_length(node->args) == 2);
appendStringInfoChar(buf, '(');
deparseExpr(linitial(node->args), context);
appendStringInfoString(buf, " IS DISTINCT FROM ");
deparseExpr(lsecond(node->args), context);
appendStringInfoChar(buf, ')');
}
/*
* Deparse given ScalarArrayOpExpr expression. To avoid problems
* around priority of operations, we always parenthesize the arguments.
*/
static void
deparseScalarArrayOpExpr(ScalarArrayOpExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
HeapTuple tuple;
Form_pg_operator form;
Expr *arg1;
Expr *arg2;
/* Retrieve information about the operator from system catalog. */
tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for operator %u", node->opno);
form = (Form_pg_operator) GETSTRUCT(tuple);
/* Sanity check. */
Assert(list_length(node->args) == 2);
/* Always parenthesize the expression. */
appendStringInfoChar(buf, '(');
/* Deparse left operand. */
arg1 = linitial(node->args);
deparseExpr(arg1, context);
appendStringInfoChar(buf, ' ');
/* Deparse operator name plus decoration. */
deparseOperatorName(buf, form);
appendStringInfo(buf, " %s (", node->useOr ? "ANY" : "ALL");
/* Deparse right operand. */
arg2 = lsecond(node->args);
deparseExpr(arg2, context);
appendStringInfoChar(buf, ')');
/* Always parenthesize the expression. */
appendStringInfoChar(buf, ')');
ReleaseSysCache(tuple);
}
/*
* Deparse a RelabelType (binary-compatible cast) node.
*/
static void
deparseRelabelType(RelabelType *node, deparse_expr_cxt *context)
{
deparseExpr(node->arg, context);
if (node->relabelformat != COERCE_IMPLICIT_CAST)
appendStringInfo(context->buf, "::%s",
deparse_type_name(node->resulttype,
node->resulttypmod));
}
/*
* Deparse a BoolExpr node.
*/
static void
deparseBoolExpr(BoolExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
const char *op = NULL; /* keep compiler quiet */
bool first;
ListCell *lc;
switch (node->boolop)
{
case AND_EXPR:
op = "AND";
break;
case OR_EXPR:
op = "OR";
break;
case NOT_EXPR:
appendStringInfoString(buf, "(NOT ");
deparseExpr(linitial(node->args), context);
appendStringInfoChar(buf, ')');
return;
}
appendStringInfoChar(buf, '(');
first = true;
foreach(lc, node->args)
{
if (!first)
appendStringInfo(buf, " %s ", op);
deparseExpr((Expr *) lfirst(lc), context);
first = false;
}
appendStringInfoChar(buf, ')');
}
/*
* Deparse IS [NOT] NULL expression.
*/
static void
deparseNullTest(NullTest *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
appendStringInfoChar(buf, '(');
deparseExpr(node->arg, context);
/*
* For scalar inputs, we prefer to print as IS [NOT] NULL, which is
* shorter and traditional. If it's a rowtype input but we're applying a
* scalar test, must print IS [NOT] DISTINCT FROM NULL to be semantically
* correct.
*/
if (node->argisrow || !type_is_rowtype(exprType((Node *) node->arg)))
{
if (node->nulltesttype == IS_NULL)
appendStringInfoString(buf, " IS NULL)");
else
appendStringInfoString(buf, " IS NOT NULL)");
}
else
{
if (node->nulltesttype == IS_NULL)
appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL)");
else
appendStringInfoString(buf, " IS DISTINCT FROM NULL)");
}
}
/*
* Deparse ARRAY[...] construct.
*/
static void
deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
bool first = true;
ListCell *lc;
appendStringInfoString(buf, "ARRAY[");
foreach(lc, node->elements)
{
if (!first)
appendStringInfoString(buf, ", ");
deparseExpr(lfirst(lc), context);
first = false;
}
appendStringInfoChar(buf, ']');
/* If the array is empty, we need an explicit cast to the array type. */
if (node->elements == NIL)
appendStringInfo(buf, "::%s",
deparse_type_name(node->array_typeid, -1));
}
/*
* Deparse an Aggref node.
*/
static void
deparseAggref(Aggref *node, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
bool use_variadic;
/* Only basic, non-split aggregation accepted. */
Assert(node->aggsplit == AGGSPLIT_SIMPLE);
/* Check if need to print VARIADIC (cf. ruleutils.c) */
use_variadic = node->aggvariadic;
/* Find aggregate name from aggfnoid which is a pg_proc entry */
appendFunctionName(node->aggfnoid, context);
appendStringInfoChar(buf, '(');
/* Add DISTINCT */
appendStringInfoString(buf, (node->aggdistinct != NIL) ? "DISTINCT " : "");
if (AGGKIND_IS_ORDERED_SET(node->aggkind))
{
/* Add WITHIN GROUP (ORDER BY ..) */
ListCell *arg;
bool first = true;
Assert(!node->aggvariadic);
Assert(node->aggorder != NIL);
foreach(arg, node->aggdirectargs)
{
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseExpr((Expr *) lfirst(arg), context);
}
appendStringInfoString(buf, ") WITHIN GROUP (ORDER BY ");
appendAggOrderBy(node->aggorder, node->args, context);
}
else
{
/* aggstar can be set only in zero-argument aggregates */
if (node->aggstar)
appendStringInfoChar(buf, '*');
else
{
ListCell *arg;
bool first = true;
/* Add all the arguments */
foreach(arg, node->args)
{
TargetEntry *tle = (TargetEntry *) lfirst(arg);
Node *n = (Node *) tle->expr;
if (tle->resjunk)
continue;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
/* Add VARIADIC */
if (use_variadic && lnext(node->args, arg) == NULL)
appendStringInfoString(buf, "VARIADIC ");
deparseExpr((Expr *) n, context);
}
}
/* Add ORDER BY */
if (node->aggorder != NIL)
{
appendStringInfoString(buf, " ORDER BY ");
appendAggOrderBy(node->aggorder, node->args, context);
}
}
/* Add FILTER (WHERE ..) */
if (node->aggfilter != NULL)
{
appendStringInfoString(buf, ") FILTER (WHERE ");
deparseExpr((Expr *) node->aggfilter, context);
}
appendStringInfoChar(buf, ')');
}
/*
* Append ORDER BY within aggregate function.
*/
static void
appendAggOrderBy(List *orderList, List *targetList, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
ListCell *lc;
bool first = true;
foreach(lc, orderList)
{
SortGroupClause *srt = (SortGroupClause *) lfirst(lc);
Node *sortexpr;
Oid sortcoltype;
TypeCacheEntry *typentry;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
sortexpr = deparseSortGroupClause(srt->tleSortGroupRef, targetList,
false, context);
sortcoltype = exprType(sortexpr);
/* See whether operator is default < or > for datatype */
typentry = lookup_type_cache(sortcoltype,
TYPECACHE_LT_OPR | TYPECACHE_GT_OPR);
if (srt->sortop == typentry->lt_opr)
appendStringInfoString(buf, " ASC");
else if (srt->sortop == typentry->gt_opr)
appendStringInfoString(buf, " DESC");
else
{
HeapTuple opertup;
Form_pg_operator operform;
appendStringInfoString(buf, " USING ");
/* Append operator name. */
opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(srt->sortop));
if (!HeapTupleIsValid(opertup))
elog(ERROR, "cache lookup failed for operator %u", srt->sortop);
operform = (Form_pg_operator) GETSTRUCT(opertup);
deparseOperatorName(buf, operform);
ReleaseSysCache(opertup);
}
if (srt->nulls_first)
appendStringInfoString(buf, " NULLS FIRST");
else
appendStringInfoString(buf, " NULLS LAST");
}
}
/*
* Print the representation of a parameter to be sent to the remote side.
*
* Note: we always label the Param's type explicitly rather than relying on
* transmitting a numeric type OID in PQexecParams(). This allows us to
* avoid assuming that types have the same OIDs on the remote side as they
* do locally --- they need only have the same names.
*/
static void
printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
char *ptypename = deparse_type_name(paramtype, paramtypmod);
appendStringInfo(buf, "$%d::%s", paramindex, ptypename);
}
/*
* Print the representation of a placeholder for a parameter that will be
* sent to the remote side at execution time.
*
* This is used when we're just trying to EXPLAIN the remote query.
* We don't have the actual value of the runtime parameter yet, and we don't
* want the remote planner to generate a plan that depends on such a value
* anyway. Thus, we can't do something simple like "$1::paramtype".
* Instead, we emit "((SELECT null::paramtype)::paramtype)".
* In all extant versions of Postgres, the planner will see that as an unknown
* constant value, which is what we want. This might need adjustment if we
* ever make the planner flatten scalar subqueries. Note: the reason for the
* apparently useless outer cast is to ensure that the representation as a
* whole will be parsed as an a_expr and not a select_with_parens; the latter
* would do the wrong thing in the context "x = ANY(...)".
*/
static void
printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
char *ptypename = deparse_type_name(paramtype, paramtypmod);
appendStringInfo(buf, "((SELECT null::%s)::%s)", ptypename, ptypename);
}
/*
* Deparse GROUP BY clause.
*/
static void
appendGroupByClause(List *tlist, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
Query *query = context->root->parse;
ListCell *lc;
bool first = true;
/* Nothing to be done, if there's no GROUP BY clause in the query. */
if (!query->groupClause)
return;
appendStringInfoString(buf, " GROUP BY ");
/*
* Queries with grouping sets are not pushed down, so we don't expect
* grouping sets here.
*/
Assert(!query->groupingSets);
foreach(lc, query->groupClause)
{
SortGroupClause *grp = (SortGroupClause *) lfirst(lc);
if (!first)
appendStringInfoString(buf, ", ");
first = false;
deparseSortGroupClause(grp->tleSortGroupRef, tlist, true, context);
}
}
/*
* Deparse ORDER BY clause according to the given pathkeys for given base
* relation. From given pathkeys expressions belonging entirely to the given
* base relation are obtained and deparsed.
*/
static void
appendOrderByClause(List *pathkeys, bool has_final_sort,
deparse_expr_cxt *context)
{
ListCell *lcell;
int nestlevel;
char *delim = " ";
RelOptInfo *baserel = context->scanrel;
StringInfo buf = context->buf;
/* Make sure any constants in the exprs are printed portably */
nestlevel = set_transmission_modes();
appendStringInfoString(buf, " ORDER BY");
foreach(lcell, pathkeys)
{
PathKey *pathkey = lfirst(lcell);
Expr *em_expr;
if (has_final_sort)
{
/*
* By construction, context->foreignrel is the input relation to
* the final sort.
*/
em_expr = find_em_expr_for_input_target(context->root,
pathkey->pk_eclass,
context->foreignrel->reltarget);
}
else
em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
Assert(em_expr != NULL);
appendStringInfoString(buf, delim);
deparseExpr(em_expr, context);
if (pathkey->pk_strategy == BTLessStrategyNumber)
appendStringInfoString(buf, " ASC");
else
appendStringInfoString(buf, " DESC");
if (pathkey->pk_nulls_first)
appendStringInfoString(buf, " NULLS FIRST");
else
appendStringInfoString(buf, " NULLS LAST");
delim = ", ";
}
reset_transmission_modes(nestlevel);
}
/*
* Deparse LIMIT/OFFSET clause.
*/
static void
appendLimitClause(deparse_expr_cxt *context)
{
PlannerInfo *root = context->root;
StringInfo buf = context->buf;
int nestlevel;
/* Make sure any constants in the exprs are printed portably */
nestlevel = set_transmission_modes();
if (root->parse->limitCount)
{
appendStringInfoString(buf, " LIMIT ");
deparseExpr((Expr *) root->parse->limitCount, context);
}
if (root->parse->limitOffset)
{
appendStringInfoString(buf, " OFFSET ");
deparseExpr((Expr *) root->parse->limitOffset, context);
}
reset_transmission_modes(nestlevel);
}
/*
* appendFunctionName
* Deparses function name from given function oid.
*/
static void
appendFunctionName(Oid funcid, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
HeapTuple proctup;
Form_pg_proc procform;
const char *proname;
proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
if (!HeapTupleIsValid(proctup))
elog(ERROR, "cache lookup failed for function %u", funcid);
procform = (Form_pg_proc) GETSTRUCT(proctup);
/* Print schema name only if it's not pg_catalog */
if (procform->pronamespace != PG_CATALOG_NAMESPACE)
{
const char *schemaname;
schemaname = get_namespace_name(procform->pronamespace);
appendStringInfo(buf, "%s.", quote_identifier(schemaname));
}
/* Always print the function name */
proname = NameStr(procform->proname);
appendStringInfoString(buf, quote_identifier(proname));
ReleaseSysCache(proctup);
}
/*
* Appends a sort or group clause.
*
* Like get_rule_sortgroupclause(), returns the expression tree, so caller
* need not find it again.
*/
static Node *
deparseSortGroupClause(Index ref, List *tlist, bool force_colno,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
TargetEntry *tle;
Expr *expr;
tle = get_sortgroupref_tle(ref, tlist);
expr = tle->expr;
if (force_colno)
{
/* Use column-number form when requested by caller. */
Assert(!tle->resjunk);
appendStringInfo(buf, "%d", tle->resno);
}
else if (expr && IsA(expr, Const))
{
/*
* Force a typecast here so that we don't emit something like "GROUP
* BY 2", which will be misconstrued as a column position rather than
* a constant.
*/
deparseConst((Const *) expr, context, 1);
}
else if (!expr || IsA(expr, Var))
deparseExpr(expr, context);
else
{
/* Always parenthesize the expression. */
appendStringInfoChar(buf, '(');
deparseExpr(expr, context);
appendStringInfoChar(buf, ')');
}
return (Node *) expr;
}
/*
* Returns true if given Var is deparsed as a subquery output column, in
* which case, *relno and *colno are set to the IDs for the relation and
* column alias to the Var provided by the subquery.
*/
static bool
is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno, int *colno)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
RelOptInfo *outerrel = fpinfo->outerrel;
RelOptInfo *innerrel = fpinfo->innerrel;
/* Should only be called in these cases. */
Assert(IS_SIMPLE_REL(foreignrel) || IS_JOIN_REL(foreignrel));
/*
* If the given relation isn't a join relation, it doesn't have any lower
* subqueries, so the Var isn't a subquery output column.
*/
if (!IS_JOIN_REL(foreignrel))
return false;
/*
* If the Var doesn't belong to any lower subqueries, it isn't a subquery
* output column.
*/
if (!bms_is_member(node->varno, fpinfo->lower_subquery_rels))
return false;
if (bms_is_member(node->varno, outerrel->relids))
{
/*
* If outer relation is deparsed as a subquery, the Var is an output
* column of the subquery; get the IDs for the relation/column alias.
*/
if (fpinfo->make_outerrel_subquery)
{
get_relation_column_alias_ids(node, outerrel, relno, colno);
return true;
}
/* Otherwise, recurse into the outer relation. */
return is_subquery_var(node, outerrel, relno, colno);
}
else
{
Assert(bms_is_member(node->varno, innerrel->relids));
/*
* If inner relation is deparsed as a subquery, the Var is an output
* column of the subquery; get the IDs for the relation/column alias.
*/
if (fpinfo->make_innerrel_subquery)
{
get_relation_column_alias_ids(node, innerrel, relno, colno);
return true;
}
/* Otherwise, recurse into the inner relation. */
return is_subquery_var(node, innerrel, relno, colno);
}
}
/*
* Get the IDs for the relation and column alias to given Var belonging to
* given relation, which are returned into *relno and *colno.
*/
static void
get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
int *relno, int *colno)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
int i;
ListCell *lc;
/* Get the relation alias ID */
*relno = fpinfo->relation_index;
/* Get the column alias ID */
i = 1;
foreach(lc, foreignrel->reltarget->exprs)
{
if (equal(lfirst(lc), (Node *) node))
{
*colno = i;
return;
}
i++;
}
/* Shouldn't get here */
elog(ERROR, "unexpected expression in subquery output");
}
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