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postgresql/contrib/postgres_fdw/deparse.c
Robert Haas b30fb56b07 postgres_fdw: Push down FULL JOINs with restriction clauses. 
The previous deparsing logic wasn't smart enough to produce subqueries
when deparsing; make it smart enough to do that.  However, we only do
it that way when necessary, because it generates more complicated SQL
which will be harder for any humans reading the queries to understand.

Etsuro Fujita, reviewed by Ashutosh Bapat

Discussion: http://postgr.es/m/c449261a-b033-dc02-9254-2fe5b7044795@lab.ntt.co.jp
2017-03-16 13:34:59 -04:00

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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) 2012-2017, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/deparse.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "postgres_fdw.h"
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/sysattr.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/clauses.h"
#include "optimizer/prep.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
#include "parser/parsetree.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,
PlannerInfo *root,
Index rtindex,
Relation rel,
bool is_returning,
Bitmapset *attrs_used,
bool qualify_col,
List **retrieved_attrs);
static void deparseExplicitTargetList(List *tlist, List **retrieved_attrs,
deparse_expr_cxt *context);
static void deparseSubqueryTargetList(deparse_expr_cxt *context);
static void deparseReturningList(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
bool trig_after_row,
List *returningList,
List **retrieved_attrs);
static void deparseColumnRef(StringInfo buf, int varno, int varattno,
PlannerInfo *root, 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 deparseArrayRef(ArrayRef *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, deparse_expr_cxt *context);
static void appendConditions(List *exprs, deparse_expr_cxt *context);
static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
RelOptInfo *joinrel, bool use_alias, List **params_list);
static void deparseFromExpr(List *quals, deparse_expr_cxt *context);
static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, bool make_subquery,
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,
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 = (RestrictInfo *) lfirst(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 (baserel->reloptkind == RELOPT_UPPER_REL)
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 and oid 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 &&
var->varattno != ObjectIdAttributeNumber)
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;
/*
* 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_ArrayRef:
{
ArrayRef *ar = (ArrayRef *) node;
/* Assignment should not be in restrictions. */
if (ar->refassgnexpr != NULL)
return false;
/*
* Recurse to remaining subexpressions. Since the array
* subscripts must yield (noncollatable) integers, they won't
* affect the inner_cxt state.
*/
if (!foreign_expr_walker((Node *) ar->refupperindexpr,
glob_cxt, &inner_cxt))
return false;
if (!foreign_expr_walker((Node *) ar->reflowerindexpr,
glob_cxt, &inner_cxt))
return false;
if (!foreign_expr_walker((Node *) ar->refexpr,
glob_cxt, &inner_cxt))
return false;
/*
* Array subscripting should yield same collation as input,
* but for safety use same logic as for function nodes.
*/
collation = ar->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 (glob_cxt->foreignrel->reloptkind != RELOPT_UPPER_REL)
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;
}
/*
* 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)
{
if (is_builtin(type_oid))
return format_type_with_typemod(type_oid, typemod);
else
return format_type_with_typemod_qualified(type_oid, typemod);
}
/*
* 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;
/*
* For an upper relation, we have already built the target list while
* checking shippability, so just return that.
*/
if (foreignrel->reloptkind == RELOPT_UPPER_REL)
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));
tlist = add_to_flat_tlist(tlist,
pull_var_clause((Node *) fpinfo->local_conds,
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.
*/
extern void
deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
List *tlist, List *remote_conds, List *pathkeys,
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(rel->reloptkind == RELOPT_JOINREL ||
rel->reloptkind == RELOPT_BASEREL ||
rel->reloptkind == RELOPT_OTHER_MEMBER_REL ||
rel->reloptkind == RELOPT_UPPER_REL);
/* Fill portions of context common to upper, join and base relation */
context.buf = buf;
context.root = root;
context.foreignrel = rel;
context.scanrel = (rel->reloptkind == RELOPT_UPPER_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 (rel->reloptkind == RELOPT_UPPER_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 (rel->reloptkind == RELOPT_UPPER_REL)
{
/* Append GROUP BY clause */
appendGroupByClause(tlist, &context);
/* Append HAVING clause */
if (remote_conds)
{
appendStringInfo(buf, " HAVING ");
appendConditions(remote_conds, &context);
}
}
/* Add ORDER BY clause if we found any useful pathkeys */
if (pathkeys)
appendOrderByClause(pathkeys, &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 (foreignrel->reloptkind == RELOPT_JOINREL ||
foreignrel->reloptkind == RELOPT_UPPER_REL)
{
/*
* For a join or upper relation the input tlist gives the list of
* columns required to be fetched from the foreign server.
*/
deparseExplicitTargetList(tlist, 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 = heap_open(rte->relid, NoLock);
deparseTargetList(buf, root, foreignrel->relid, rel, false,
fpinfo->attrs_used, false, retrieved_attrs);
heap_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.
*/
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(context->foreignrel->reloptkind != RELOPT_UPPER_REL ||
scanrel->reloptkind == RELOPT_JOINREL ||
scanrel->reloptkind == RELOPT_BASEREL);
/* Construct FROM clause */
appendStringInfoString(buf, " FROM ");
deparseFromExprForRel(buf, context->root, scanrel,
(bms_num_members(scanrel->relids) > 1),
context->params_list);
/* Construct WHERE clause */
if (quals != NIL)
{
appendStringInfo(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,
PlannerInfo *root,
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 = tupdesc->attrs[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, root, qualify_col);
*retrieved_attrs = lappend_int(*retrieved_attrs, i);
}
}
/*
* Add ctid and oid 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);
}
if (bms_is_member(ObjectIdAttributeNumber - 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, "oid");
*retrieved_attrs = lappend_int(*retrieved_attrs,
ObjectIdAttributeNumber);
}
/* 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 (rel->reloptkind == RELOPT_JOINREL)
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_num_members(rel->relids) > 1 &&
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.
*/
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. See comments in
* declaration of PgFdwRelationInfo for details.
*/
if (IsA(expr, RestrictInfo))
{
RestrictInfo *ri = (RestrictInfo *) expr;
expr = ri->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 */
extern 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.
*/
static void
deparseExplicitTargetList(List *tlist, List **retrieved_attrs,
deparse_expr_cxt *context)
{
ListCell *lc;
StringInfo buf = context->buf;
int i = 0;
*retrieved_attrs = NIL;
foreach(lc, tlist)
{
TargetEntry *tle = castNode(TargetEntry, lfirst(lc));
if (i > 0)
appendStringInfoString(buf, ", ");
deparseExpr((Expr *) tle->expr, context);
*retrieved_attrs = lappend_int(*retrieved_attrs, i + 1);
i++;
}
if (i == 0)
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(foreignrel->reloptkind == RELOPT_BASEREL ||
foreignrel->reloptkind == RELOPT_JOINREL);
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.
*/
static void
deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
bool use_alias, List **params_list)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
if (foreignrel->reloptkind == RELOPT_JOINREL)
{
StringInfoData join_sql_o;
StringInfoData join_sql_i;
/* Deparse outer relation */
initStringInfo(&join_sql_o);
deparseRangeTblRef(&join_sql_o, root, fpinfo->outerrel,
fpinfo->make_outerrel_subquery, params_list);
/* Deparse inner relation */
initStringInfo(&join_sql_i);
deparseRangeTblRef(&join_sql_i, root, fpinfo->innerrel,
fpinfo->make_innerrel_subquery, params_list);
/*
* 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;
appendStringInfo(buf, "(");
appendConditions(fpinfo->joinclauses, &context);
appendStringInfo(buf, ")");
}
else
appendStringInfoString(buf, "(TRUE)");
/* End the FROM clause entry. */
appendStringInfo(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 = heap_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);
heap_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, List **params_list)
{
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
/* Should only be called in these cases. */
Assert(foreignrel->reloptkind == RELOPT_BASEREL ||
foreignrel->reloptkind == RELOPT_JOINREL);
Assert(fpinfo->local_conds == NIL);
/* If make_subquery is true, deparse the relation as a subquery. */
if (make_subquery)
{
List *retrieved_attrs;
int ncols;
/* Deparse the subquery representing the relation. */
appendStringInfoChar(buf, '(');
deparseSelectStmtForRel(buf, root, foreignrel, NIL,
fpinfo->remote_conds, NIL, 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, 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 RETURNING (if any), which is returned
* to *retrieved_attrs.
*/
void
deparseInsertSql(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *targetAttrs, bool doNothing,
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, root, 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, root, rtindex, rel,
rel->trigdesc && rel->trigdesc->trig_insert_after_row,
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 RETURNING (if any), which is returned
* to *retrieved_attrs.
*/
void
deparseUpdateSql(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *targetAttrs, 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, root, false);
appendStringInfo(buf, " = $%d", pindex);
pindex++;
}
appendStringInfoString(buf, " WHERE ctid = $1");
deparseReturningList(buf, root, rtindex, rel,
rel->trigdesc && rel->trigdesc->trig_update_after_row,
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 RETURNING (if any), which is returned
* to *retrieved_attrs.
*/
void
deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *targetlist,
List *targetAttrs,
List *remote_conds,
List **params_list,
List *returningList,
List **retrieved_attrs)
{
RelOptInfo *baserel = root->simple_rel_array[rtindex];
deparse_expr_cxt context;
int nestlevel;
bool first;
ListCell *lc;
/* Set up context struct for recursion */
context.root = root;
context.foreignrel = baserel;
context.scanrel = baserel;
context.buf = buf;
context.params_list = params_list;
appendStringInfoString(buf, "UPDATE ");
deparseRelation(buf, rel);
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, root, false);
appendStringInfoString(buf, " = ");
deparseExpr((Expr *) tle->expr, &context);
}
reset_transmission_modes(nestlevel);
if (remote_conds)
{
appendStringInfo(buf, " WHERE ");
appendConditions(remote_conds, &context);
}
deparseReturningList(buf, root, rtindex, rel, false,
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, PlannerInfo *root,
Index rtindex, Relation rel,
List *returningList,
List **retrieved_attrs)
{
appendStringInfoString(buf, "DELETE FROM ");
deparseRelation(buf, rel);
appendStringInfoString(buf, " WHERE ctid = $1");
deparseReturningList(buf, root, rtindex, rel,
rel->trigdesc && rel->trigdesc->trig_delete_after_row,
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
deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
List *remote_conds,
List **params_list,
List *returningList,
List **retrieved_attrs)
{
RelOptInfo *baserel = root->simple_rel_array[rtindex];
deparse_expr_cxt context;
/* Set up context struct for recursion */
context.root = root;
context.foreignrel = baserel;
context.scanrel = baserel;
context.buf = buf;
context.params_list = params_list;
appendStringInfoString(buf, "DELETE FROM ");
deparseRelation(buf, rel);
if (remote_conds)
{
appendStringInfo(buf, " WHERE ");
appendConditions(remote_conds, &context);
}
deparseReturningList(buf, root, rtindex, rel, false,
returningList, retrieved_attrs);
}
/*
* Add a RETURNING clause, if needed, to an INSERT/UPDATE/DELETE.
*/
static void
deparseReturningList(StringInfo buf, PlannerInfo *root,
Index rtindex, Relation rel,
bool trig_after_row,
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 (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, root, 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 (tupdesc->attrs[i]->attisdropped)
continue;
if (!first)
appendStringInfoString(buf, ", ");
first = false;
/* Use attribute name or column_name option. */
colname = NameStr(tupdesc->attrs[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, PlannerInfo *root,
bool qualify_col)
{
RangeTblEntry *rte;
/* 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 == ObjectIdAttributeNumber)
{
if (qualify_col)
ADD_REL_QUALIFIER(buf, varno);
appendStringInfoString(buf, "oid");
}
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)
{
rte = planner_rt_fetch(varno, root);
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;
/* Get RangeTblEntry from array in PlannerInfo. */
rte = planner_rt_fetch(varno, root);
/*
* The lock on the relation will be held by upper callers, so it's
* fine to open it with no lock here.
*/
rel = heap_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);
appendStringInfo(buf, "*)::text IS NOT NULL THEN ");
}
appendStringInfoString(buf, "ROW(");
deparseTargetList(buf, root, varno, rel, false, attrs_used, qualify_col,
&retrieved_attrs);
appendStringInfoString(buf, ")");
/* Complete the CASE WHEN statement started above. */
if (qualify_col)
appendStringInfo(buf, " END");
heap_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));
/* Get RangeTblEntry from array in PlannerInfo. */
rte = planner_rt_fetch(varno, root);
/*
* 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_relid_attribute_name(rte->relid, varattno);
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_ArrayRef:
deparseArrayRef((ArrayRef *) 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_num_members(relids) > 1);
/*
* 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,
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 an array subscript expression.
*/
static void
deparseArrayRef(ArrayRef *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(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(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 */
appendStringInfo(buf, "%s", (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(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,
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;
appendStringInfo(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, 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, 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();
appendStringInfo(buf, " ORDER BY");
foreach(lcell, pathkeys)
{
PathKey *pathkey = lfirst(lcell);
Expr *em_expr;
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);
}
/*
* 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);
appendStringInfo(buf, "%s", 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, deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
TargetEntry *tle;
Expr *expr;
tle = get_sortgroupref_tle(ref, tlist);
expr = tle->expr;
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. */
appendStringInfoString(buf, "(");
deparseExpr(expr, context);
appendStringInfoString(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(foreignrel->reloptkind == RELOPT_BASEREL ||
foreignrel->reloptkind == RELOPT_JOINREL ||
foreignrel->reloptkind == RELOPT_OTHER_MEMBER_REL);
/*
* 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 (foreignrel->reloptkind != RELOPT_JOINREL)
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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