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postgresql/contrib/pg_freespacemap/pg_freespacemap.c

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/*-------------------------------------------------------------------------
*
* 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 2006/10/19 18:32:46 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 numPages; /* Max possible no. of pages in map. */
int nPages; /* Mapped pages for a relation. */
/*
* Get the free space map data structure.
*/
FreeSpaceMap = GetFreeSpaceMap();
numPages = MaxFSMPages;
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);
}
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