mirror of https://github.com/postgres/postgres
This patch only supports seq_page_cost and random_page_cost as parameters, but it provides the infrastructure to scalably support many more. In particular, we may want to add support for effective_io_concurrency, but I'm leaving that as future work for now. Thanks to Tom Lane for design help and Alvaro Herrera for the review.REL9_0_ALPHA4_BRANCH
Robert Haas
16 years ago
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72559b49c0
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/*-------------------------------------------------------------------------
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* |
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* spccache.c |
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* Tablespace cache management. |
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* |
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* We cache the parsed version of spcoptions for each tablespace to avoid |
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* needing to reparse on every lookup. Right now, there doesn't appear to |
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* be a measurable performance gain from doing this, but that might change |
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* in the future as we add more options. |
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* |
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group |
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* Portions Copyright (c) 1994, Regents of the University of California |
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* |
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* IDENTIFICATION |
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* $PostgreSQL: pgsql/src/backend/utils/cache/spccache.c,v 1.1 2010/01/05 21:53:59 rhaas Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#include "postgres.h" |
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#include "access/reloptions.h" |
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#include "catalog/pg_tablespace.h" |
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#include "commands/tablespace.h" |
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#include "miscadmin.h" |
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#include "optimizer/cost.h" |
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#include "utils/catcache.h" |
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#include "utils/hsearch.h" |
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#include "utils/inval.h" |
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#include "utils/spccache.h" |
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#include "utils/syscache.h" |
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static HTAB *TableSpaceCacheHash = NULL; |
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typedef struct { |
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Oid oid; |
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TableSpaceOpts *opts; |
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} TableSpace; |
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/*
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* InvalidateTableSpaceCacheCallback |
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* Flush all cache entries when pg_tablespace is updated. |
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* |
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* When pg_tablespace is updated, we must flush the cache entry at least |
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* for that tablespace. Currently, we just flush them all. This is quick |
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* and easy and doesn't cost much, since there shouldn't be terribly many |
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* tablespaces, nor do we expect them to be frequently modified. |
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*/ |
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static void |
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InvalidateTableSpaceCacheCallback(Datum arg, int cacheid, ItemPointer tuplePtr) |
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{ |
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HASH_SEQ_STATUS status; |
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TableSpace *spc; |
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hash_seq_init(&status, TableSpaceCacheHash); |
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while ((spc = (TableSpace *) hash_seq_search(&status)) != NULL) |
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{ |
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if (hash_search(TableSpaceCacheHash, (void *) &spc->oid, HASH_REMOVE, |
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NULL) == NULL) |
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elog(ERROR, "hash table corrupted"); |
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if (spc->opts) |
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pfree(spc->opts); |
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} |
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} |
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/*
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* InitializeTableSpaceCache |
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* Initiate the tablespace cache. |
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*/ |
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static void |
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InitializeTableSpaceCache(void) |
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{ |
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HASHCTL ctl; |
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/* Initialize the hash table. */ |
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MemSet(&ctl, 0, sizeof(ctl)); |
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ctl.keysize = sizeof(Oid); |
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ctl.entrysize = sizeof(TableSpace); |
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ctl.hash = tag_hash; |
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TableSpaceCacheHash = |
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hash_create("TableSpace cache", 16, &ctl, |
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HASH_ELEM | HASH_FUNCTION); |
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/* Make sure we've initialized CacheMemoryContext. */ |
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if (!CacheMemoryContext) |
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CreateCacheMemoryContext(); |
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/* Watch for invalidation events. */ |
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CacheRegisterSyscacheCallback(TABLESPACEOID, |
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InvalidateTableSpaceCacheCallback, |
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(Datum) 0); |
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} |
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/*
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* get_tablespace |
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* Fetch TableSpace structure for a specified table OID. |
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* |
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* Pointers returned by this function should not be stored, since a cache |
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* flush will invalidate them. |
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*/ |
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static TableSpace * |
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get_tablespace(Oid spcid) |
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{ |
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HeapTuple tp; |
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TableSpace *spc; |
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bool found; |
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/*
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* Since spcid is always from a pg_class tuple, InvalidOid implies the |
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* default. |
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*/ |
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if (spcid == InvalidOid) |
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spcid = MyDatabaseTableSpace; |
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/* Find existing cache entry, or create a new one. */ |
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if (!TableSpaceCacheHash) |
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InitializeTableSpaceCache(); |
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spc = (TableSpace *) hash_search(TableSpaceCacheHash, (void *) &spcid, |
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HASH_ENTER, &found); |
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if (found) |
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return spc; |
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/*
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* Not found in TableSpace cache. Check catcache. If we don't find a |
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* valid HeapTuple, it must mean someone has managed to request tablespace |
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* details for a non-existent tablespace. We'll just treat that case as if |
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* no options were specified. |
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*/ |
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tp = SearchSysCache(TABLESPACEOID, ObjectIdGetDatum(spcid), 0, 0, 0); |
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if (!HeapTupleIsValid(tp)) |
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spc->opts = NULL; |
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else |
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{ |
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Datum datum; |
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bool isNull; |
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MemoryContext octx; |
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datum = SysCacheGetAttr(TABLESPACEOID, |
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tp, |
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Anum_pg_tablespace_spcoptions, |
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&isNull); |
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if (isNull) |
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spc->opts = NULL; |
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else |
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{ |
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octx = MemoryContextSwitchTo(CacheMemoryContext); |
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spc->opts = (TableSpaceOpts *) tablespace_reloptions(datum, false); |
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MemoryContextSwitchTo(octx); |
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} |
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ReleaseSysCache(tp); |
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} |
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/* Update new TableSpace cache entry with results of option parsing. */ |
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return spc; |
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} |
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/*
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* get_tablespace_page_costs |
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* Return random and sequential page costs for a given tablespace. |
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*/ |
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void |
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get_tablespace_page_costs(Oid spcid, double *spc_random_page_cost, |
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double *spc_seq_page_cost) |
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{ |
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TableSpace *spc = get_tablespace(spcid); |
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Assert(spc != NULL); |
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if (spc_random_page_cost) |
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{ |
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if (!spc->opts || spc->opts->random_page_cost < 0) |
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*spc_random_page_cost = random_page_cost; |
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else |
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*spc_random_page_cost = spc->opts->random_page_cost; |
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} |
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if (spc_seq_page_cost) |
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{ |
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if (!spc->opts || spc->opts->seq_page_cost < 0) |
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*spc_seq_page_cost = seq_page_cost; |
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else |
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*spc_seq_page_cost = spc->opts->seq_page_cost; |
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} |
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} |
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@ -0,0 +1,19 @@ |
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/*-------------------------------------------------------------------------
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* |
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* spccache.h |
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* Tablespace cache. |
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* |
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group |
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* Portions Copyright (c) 1994, Regents of the University of California |
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* |
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* $PostgreSQL: pgsql/src/include/utils/spccache.h,v 1.1 2010/01/05 21:54:00 rhaas Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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#ifndef SPCCACHE_H |
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#define SPCCACHE_H |
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void get_tablespace_page_costs(Oid spcid, float8 *spc_random_page_cost, |
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float8 *spc_seq_page_cost); |
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#endif /* SPCCACHE_H */ |
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