postgresql/contrib/pg_freespacemap/pg_freespacemap.c
Tom Lane 0e7d4c0289 Fix contrib/pg_freespacemap's underestimate of the number of pages it
could find in the FSM.  Per report from Dimitri Fontaine and Andrew Gierth.

(Affects only 8.2 and 8.3 since HEAD no longer has MaxFSMPages at all.)
2009-04-07 18:11:04 +00:00

397 lines
10 KiB
C

/*-------------------------------------------------------------------------
*
* pg_freespacemap.c
* display some contents of the free space relation and page maps.
*
* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.9.2.1 2009/04/07 18:11:04 tgl Exp $
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "funcapi.h"
#include "access/heapam.h"
#include "catalog/pg_type.h"
#include "storage/freespace.h"
#define NUM_FREESPACE_PAGES_ELEM 5
#define NUM_FREESPACE_RELATIONS_ELEM 7
PG_MODULE_MAGIC;
Datum pg_freespacemap_pages(PG_FUNCTION_ARGS);
Datum pg_freespacemap_relations(PG_FUNCTION_ARGS);
/*
* Record structure holding the to be exposed per-page data.
*/
typedef struct
{
Oid reltablespace;
Oid reldatabase;
Oid relfilenode;
BlockNumber relblocknumber;
Size bytes;
bool isindex;
} FreeSpacePagesRec;
/*
* Record structure holding the to be exposed per-relation data.
*/
typedef struct
{
Oid reltablespace;
Oid reldatabase;
Oid relfilenode;
Size avgrequest;
BlockNumber interestingpages;
int storedpages;
int nextpage;
bool isindex;
} FreeSpaceRelationsRec;
/*
* Function context for page data persisting over repeated calls.
*/
typedef struct
{
TupleDesc tupdesc;
FreeSpacePagesRec *record;
} FreeSpacePagesContext;
/*
* Function context for relation data persisting over repeated calls.
*/
typedef struct
{
TupleDesc tupdesc;
FreeSpaceRelationsRec *record;
} FreeSpaceRelationsContext;
/*
* Function returning page data from the Free Space Map (FSM).
*/
PG_FUNCTION_INFO_V1(pg_freespacemap_pages);
Datum
pg_freespacemap_pages(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
Datum result;
MemoryContext oldcontext;
FreeSpacePagesContext *fctx; /* User function context. */
TupleDesc tupledesc;
HeapTuple tuple;
FSMHeader *FreeSpaceMap; /* FSM main structure. */
FSMRelation *fsmrel; /* Individual relation. */
if (SRF_IS_FIRSTCALL())
{
int i;
int nchunks; /* Size of freespace.c's arena. */
int numPages; /* Max possible no. of pages in map. */
int nPages; /* Mapped pages for a relation. */
/*
* Get the free space map data structure.
*/
FreeSpaceMap = GetFreeSpaceMap();
/* this must match calculation in InitFreeSpaceMap(): */
nchunks = (MaxFSMPages - 1) / CHUNKPAGES + 1;
/* Worst case (lots of indexes) could have this many pages: */
numPages = nchunks * INDEXCHUNKPAGES;
funcctx = SRF_FIRSTCALL_INIT();
/* Switch context when allocating stuff to be used in later calls */
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/*
* Create a function context for cross-call persistence.
*/
fctx = (FreeSpacePagesContext *) palloc(sizeof(FreeSpacePagesContext));
funcctx->user_fctx = fctx;
/* Construct a tuple descriptor for the result rows. */
tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_PAGES_ELEM, false);
TupleDescInitEntry(tupledesc, (AttrNumber) 1, "reltablespace",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 2, "reldatabase",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 3, "relfilenode",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 4, "relblocknumber",
INT8OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 5, "bytes",
INT4OID, -1, 0);
fctx->tupdesc = BlessTupleDesc(tupledesc);
/*
* Allocate numPages worth of FreeSpacePagesRec records, this is an
* upper bound.
*/
fctx->record = (FreeSpacePagesRec *) palloc(sizeof(FreeSpacePagesRec) * numPages);
/* Return to original context when allocating transient memory */
MemoryContextSwitchTo(oldcontext);
/*
* Lock free space map and scan though all the relations. For each
* relation, gets all its mapped pages.
*/
LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
i = 0;
for (fsmrel = FreeSpaceMap->usageList; fsmrel; fsmrel = fsmrel->nextUsage)
{
if (fsmrel->isIndex)
{
/* Index relation. */
IndexFSMPageData *page;
page = (IndexFSMPageData *)
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
{
fctx->record[i].reltablespace = fsmrel->key.spcNode;
fctx->record[i].reldatabase = fsmrel->key.dbNode;
fctx->record[i].relfilenode = fsmrel->key.relNode;
fctx->record[i].relblocknumber = IndexFSMPageGetPageNum(page);
fctx->record[i].bytes = 0;
fctx->record[i].isindex = true;
page++;
i++;
}
}
else
{
/* Heap relation. */
FSMPageData *page;
page = (FSMPageData *)
(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
{
fctx->record[i].reltablespace = fsmrel->key.spcNode;
fctx->record[i].reldatabase = fsmrel->key.dbNode;
fctx->record[i].relfilenode = fsmrel->key.relNode;
fctx->record[i].relblocknumber = FSMPageGetPageNum(page);
fctx->record[i].bytes = FSMPageGetSpace(page);
fctx->record[i].isindex = false;
page++;
i++;
}
}
}
/* Release free space map. */
LWLockRelease(FreeSpaceLock);
/* Set the real no. of calls as we know it now! */
Assert(i <= numPages);
funcctx->max_calls = i;
}
funcctx = SRF_PERCALL_SETUP();
/* Get the saved state */
fctx = funcctx->user_fctx;
if (funcctx->call_cntr < funcctx->max_calls)
{
int i = funcctx->call_cntr;
FreeSpacePagesRec *record = &fctx->record[i];
Datum values[NUM_FREESPACE_PAGES_ELEM];
bool nulls[NUM_FREESPACE_PAGES_ELEM];
values[0] = ObjectIdGetDatum(record->reltablespace);
nulls[0] = false;
values[1] = ObjectIdGetDatum(record->reldatabase);
nulls[1] = false;
values[2] = ObjectIdGetDatum(record->relfilenode);
nulls[2] = false;
values[3] = Int64GetDatum((int64) record->relblocknumber);
nulls[3] = false;
/*
* Set (free) bytes to NULL for an index relation.
*/
if (record->isindex)
{
nulls[4] = true;
}
else
{
values[4] = UInt32GetDatum(record->bytes);
nulls[4] = false;
}
/* Build and return the tuple. */
tuple = heap_form_tuple(fctx->tupdesc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
else
SRF_RETURN_DONE(funcctx);
}
/*
* Function returning relation data from the Free Space Map (FSM).
*/
PG_FUNCTION_INFO_V1(pg_freespacemap_relations);
Datum
pg_freespacemap_relations(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
Datum result;
MemoryContext oldcontext;
FreeSpaceRelationsContext *fctx; /* User function context. */
TupleDesc tupledesc;
HeapTuple tuple;
FSMHeader *FreeSpaceMap; /* FSM main structure. */
FSMRelation *fsmrel; /* Individual relation. */
if (SRF_IS_FIRSTCALL())
{
int i;
int numRelations; /* Max no. of Relations in map. */
/*
* Get the free space map data structure.
*/
FreeSpaceMap = GetFreeSpaceMap();
numRelations = MaxFSMRelations;
funcctx = SRF_FIRSTCALL_INIT();
/* Switch context when allocating stuff to be used in later calls */
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/*
* Create a function context for cross-call persistence.
*/
fctx = (FreeSpaceRelationsContext *) palloc(sizeof(FreeSpaceRelationsContext));
funcctx->user_fctx = fctx;
/* Construct a tuple descriptor for the result rows. */
tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_RELATIONS_ELEM, false);
TupleDescInitEntry(tupledesc, (AttrNumber) 1, "reltablespace",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 2, "reldatabase",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 3, "relfilenode",
OIDOID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 4, "avgrequest",
INT4OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 5, "interestingpages",
INT4OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 6, "storedpages",
INT4OID, -1, 0);
TupleDescInitEntry(tupledesc, (AttrNumber) 7, "nextpage",
INT4OID, -1, 0);
fctx->tupdesc = BlessTupleDesc(tupledesc);
/*
* Allocate numRelations worth of FreeSpaceRelationsRec records, this
* is also an upper bound.
*/
fctx->record = (FreeSpaceRelationsRec *) palloc(sizeof(FreeSpaceRelationsRec) * numRelations);
/* Return to original context when allocating transient memory */
MemoryContextSwitchTo(oldcontext);
/*
* Lock free space map and scan though all the relations.
*/
LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
i = 0;
for (fsmrel = FreeSpaceMap->usageList; fsmrel; fsmrel = fsmrel->nextUsage)
{
fctx->record[i].reltablespace = fsmrel->key.spcNode;
fctx->record[i].reldatabase = fsmrel->key.dbNode;
fctx->record[i].relfilenode = fsmrel->key.relNode;
fctx->record[i].avgrequest = (int64) fsmrel->avgRequest;
fctx->record[i].interestingpages = fsmrel->interestingPages;
fctx->record[i].storedpages = fsmrel->storedPages;
fctx->record[i].nextpage = fsmrel->nextPage;
fctx->record[i].isindex = fsmrel->isIndex;
i++;
}
/* Release free space map. */
LWLockRelease(FreeSpaceLock);
/* Set the real no. of calls as we know it now! */
Assert(i <= numRelations);
funcctx->max_calls = i;
}
funcctx = SRF_PERCALL_SETUP();
/* Get the saved state */
fctx = funcctx->user_fctx;
if (funcctx->call_cntr < funcctx->max_calls)
{
int i = funcctx->call_cntr;
FreeSpaceRelationsRec *record = &fctx->record[i];
Datum values[NUM_FREESPACE_RELATIONS_ELEM];
bool nulls[NUM_FREESPACE_RELATIONS_ELEM];
values[0] = ObjectIdGetDatum(record->reltablespace);
nulls[0] = false;
values[1] = ObjectIdGetDatum(record->reldatabase);
nulls[1] = false;
values[2] = ObjectIdGetDatum(record->relfilenode);
nulls[2] = false;
/*
* avgrequest isn't meaningful for an index
*/
if (record->isindex)
{
nulls[3] = true;
}
else
{
values[3] = UInt32GetDatum(record->avgrequest);
nulls[3] = false;
}
values[4] = Int32GetDatum(record->interestingpages);
nulls[4] = false;
values[5] = Int32GetDatum(record->storedpages);
nulls[5] = false;
values[6] = Int32GetDatum(record->nextpage);
nulls[6] = false;
/* Build and return the tuple. */
tuple = heap_form_tuple(fctx->tupdesc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
else
SRF_RETURN_DONE(funcctx);
}