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Add contrib/pg_freespacemap to display free space map information.
Mark Kirkwood
This commit is contained in:
Bruce Momjian
231
contrib/pg_freespacemap/pg_freespacemap.c
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231
contrib/pg_freespacemap/pg_freespacemap.c
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/*-------------------------------------------------------------------------
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*
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* pg_freespacemap.c
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* display some contents of the free space map.
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*
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* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.1 2006/02/12 03:55:53 momjian Exp $
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "funcapi.h"
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#include "catalog/pg_type.h"
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#include "storage/freespace.h"
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#include "utils/relcache.h"
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#define NUM_FREESPACE_PAGES_ELEM 6
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#if defined(WIN32) || defined(__CYGWIN__)
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extern DLLIMPORT volatile uint32 InterruptHoldoffCount;
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#endif
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Datum pg_freespacemap(PG_FUNCTION_ARGS);
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/*
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* Record structure holding the to be exposed free space data.
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*/
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typedef struct
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{
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uint32 blockid;
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uint32 relfilenode;
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uint32 reltablespace;
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uint32 reldatabase;
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uint32 relblocknumber;
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uint32 blockfreebytes;
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} FreeSpacePagesRec;
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/*
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* Function context for data persisting over repeated calls.
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*/
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typedef struct
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{
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AttInMetadata *attinmeta;
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FreeSpacePagesRec *record;
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char *values[NUM_FREESPACE_PAGES_ELEM];
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} FreeSpacePagesContext;
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/*
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* Function returning data from the Free Space Map (FSM).
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*/
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PG_FUNCTION_INFO_V1(pg_freespacemap);
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Datum
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pg_freespacemap(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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Datum result;
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MemoryContext oldcontext;
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FreeSpacePagesContext *fctx; /* User function context. */
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TupleDesc tupledesc;
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HeapTuple tuple;
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FSMHeader *FreeSpaceMap; /* FSM main structure. */
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FSMRelation *fsmrel; /* Individual relation. */
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if (SRF_IS_FIRSTCALL())
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{
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uint32 i;
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uint32 numPages; /* Max possible no. of pages in map. */
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int nPages; /* Mapped pages for a relation. */
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/*
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* Get the free space map data structure.
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*/
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FreeSpaceMap = GetFreeSpaceMap();
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numPages = MaxFSMPages;
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funcctx = SRF_FIRSTCALL_INIT();
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/* Switch context when allocating stuff to be used in later calls */
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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/* Construct a tuple to return. */
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tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_PAGES_ELEM, false);
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TupleDescInitEntry(tupledesc, (AttrNumber) 1, "blockid",
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INT4OID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 2, "relfilenode",
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OIDOID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 3, "reltablespace",
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OIDOID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 4, "reldatabase",
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OIDOID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 5, "relblocknumber",
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INT8OID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 6, "blockfreebytes",
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INT4OID, -1, 0);
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/* Generate attribute metadata needed later to produce tuples */
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funcctx->attinmeta = TupleDescGetAttInMetadata(tupledesc);
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/*
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* Create a function context for cross-call persistence and initialize
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* the counters.
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*/
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fctx = (FreeSpacePagesContext *) palloc(sizeof(FreeSpacePagesContext));
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funcctx->user_fctx = fctx;
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/* Set an upper bound on the calls */
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funcctx->max_calls = numPages;
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/* Allocate numPages worth of FreeSpacePagesRec records, this is also
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* an upper bound.
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*/
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fctx->record = (FreeSpacePagesRec *) palloc(sizeof(FreeSpacePagesRec) * numPages);
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/* allocate the strings for tuple formation */
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fctx->values[0] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[1] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[2] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[3] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[4] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[5] = (char *) palloc(3 * sizeof(uint32) + 1);
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/* Return to original context when allocating transient memory */
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MemoryContextSwitchTo(oldcontext);
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/*
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* Lock free space map and scan though all the relations,
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* for each relation, gets all its mapped pages.
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*/
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LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
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i = 0;
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for (fsmrel = FreeSpaceMap->usageList; fsmrel; fsmrel = fsmrel->nextUsage)
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{
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if (fsmrel->isIndex)
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{ /* Index relation. */
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IndexFSMPageData *page;
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page = (IndexFSMPageData *)
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(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
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for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
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{
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fctx->record[i].blockid = i;
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fctx->record[i].relfilenode = fsmrel->key.relNode;
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fctx->record[i].reltablespace = fsmrel->key.spcNode;
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fctx->record[i].reldatabase = fsmrel->key.dbNode;
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fctx->record[i].relblocknumber = IndexFSMPageGetPageNum(page);
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fctx->record[i].blockfreebytes = 0; /* index.*/
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page++;
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i++;
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}
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}
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else
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{ /* Heap relation. */
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FSMPageData *page;
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page = (FSMPageData *)
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(FreeSpaceMap->arena + fsmrel->firstChunk * CHUNKBYTES);
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for (nPages = 0; nPages < fsmrel->storedPages; nPages++)
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{
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fctx->record[i].blockid = i;
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fctx->record[i].relfilenode = fsmrel->key.relNode;
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fctx->record[i].reltablespace = fsmrel->key.spcNode;
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fctx->record[i].reldatabase = fsmrel->key.dbNode;
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fctx->record[i].relblocknumber = FSMPageGetPageNum(page);
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fctx->record[i].blockfreebytes = FSMPageGetSpace(page);
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page++;
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i++;
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}
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}
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}
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/* Set the real no. of calls as we know it now! */
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funcctx->max_calls = i;
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/* Release free space map. */
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LWLockRelease(FreeSpaceLock);
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}
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funcctx = SRF_PERCALL_SETUP();
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/* Get the saved state */
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fctx = funcctx->user_fctx;
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if (funcctx->call_cntr < funcctx->max_calls)
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{
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uint32 i = funcctx->call_cntr;
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sprintf(fctx->values[0], "%u", fctx->record[i].blockid);
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sprintf(fctx->values[1], "%u", fctx->record[i].relfilenode);
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sprintf(fctx->values[2], "%u", fctx->record[i].reltablespace);
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sprintf(fctx->values[3], "%u", fctx->record[i].reldatabase);
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sprintf(fctx->values[4], "%u", fctx->record[i].relblocknumber);
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sprintf(fctx->values[5], "%u", fctx->record[i].blockfreebytes);
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/* Build and return the tuple. */
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tuple = BuildTupleFromCStrings(funcctx->attinmeta, fctx->values);
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result = HeapTupleGetDatum(tuple);
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SRF_RETURN_NEXT(funcctx, result);
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}
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else
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SRF_RETURN_DONE(funcctx);
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}
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