/*-------------------------------------------------------------------------
*
* pg_freespacemap.c
- * display some contents of the free space relation and page maps.
+ * display contents of a free space map
*
- * $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.10 2008/05/12 00:00:43 alvherre Exp $
+ * $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.11 2008/09/30 11:17:07 heikki Exp $
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include "access/heapam.h"
#include "access/htup.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "storage/freespace.h"
-#include "storage/lmgr.h"
+#include "utils/builtins.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);
-}
-
+Datum pg_freespace(PG_FUNCTION_ARGS);
+Datum pg_freespacedump(PG_FUNCTION_ARGS);
/*
- * Function returning relation data from the Free Space Map (FSM).
+ * Returns the amount of free space on a given page, according to the
+ * free space map.
*/
-PG_FUNCTION_INFO_V1(pg_freespacemap_relations);
+PG_FUNCTION_INFO_V1(pg_freespace);
Datum
-pg_freespacemap_relations(PG_FUNCTION_ARGS)
+pg_freespace(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];
+ Oid relid = PG_GETARG_OID(0);
+ uint32 blkno = PG_GETARG_UINT32(1);
+ int16 freespace;
+ Relation rel;
- values[0] = ObjectIdGetDatum(record->reltablespace);
- nulls[0] = false;
- values[1] = ObjectIdGetDatum(record->reldatabase);
- nulls[1] = false;
- values[2] = ObjectIdGetDatum(record->relfilenode);
- nulls[2] = false;
+ rel = relation_open(relid, AccessShareLock);
- /*
- * 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;
+ if (!BlockNumberIsValid(blkno))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid block number")));
- /* Build and return the tuple. */
- tuple = heap_form_tuple(fctx->tupdesc, values, nulls);
- result = HeapTupleGetDatum(tuple);
+ freespace = GetRecordedFreeSpace(rel, blkno);
- SRF_RETURN_NEXT(funcctx, result);
- }
- else
- SRF_RETURN_DONE(funcctx);
+ relation_close(rel, AccessShareLock);
+ PG_RETURN_INT16(freespace);
}
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