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Teach SP-GiST to do index-only scans.

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Operator classes can specify whether or not they support this; this
preserves the flexibility to use lossy representations within an index.

In passing, move constant data about a given index into the rd_amcache
cache area, instead of doing fresh lookups each time we start an index
operation.  This is mainly to try to make sure that spgcanreturn() has
insignificant cost; I still don't have any proof that it matters for
actual index accesses.  Also, get rid of useless copying of FmgrInfo
pointers; we can perfectly well use the relcache's versions in-place.
This commit is contained in:
Tom Lane
2011-12-19 14:58:41 -05:00
parent 3695a55513
commit 9220362493
10 changed files with 286 additions and 172 deletions
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166
src/backend/access/spgist/spgutils.c
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@ -34,51 +34,88 @@ fillTypeDesc(SpGistTypeDesc *desc, Oid type)
get_typlenbyval(type, &desc->attlen, &desc->attbyval);
}
/*
* Fetch local cache of AM-specific info about the index, initializing it
* if necessary
*/
SpGistCache *
spgGetCache(Relation index)
{
SpGistCache *cache;
if (index->rd_amcache == NULL)
{
Oid atttype;
spgConfigIn in;
FmgrInfo *procinfo;
Buffer metabuffer;
SpGistMetaPageData *metadata;
cache = MemoryContextAllocZero(index->rd_indexcxt,
sizeof(SpGistCache));
/* SPGiST doesn't support multi-column indexes */
Assert(index->rd_att->natts == 1);
/*
* Get the actual data type of the indexed column from the index
* tupdesc. We pass this to the opclass config function so that
* polymorphic opclasses are possible.
*/
atttype = index->rd_att->attrs[0]->atttypid;
/* Call the config function to get config info for the opclass */
in.attType = atttype;
procinfo = index_getprocinfo(index, 1, SPGIST_CONFIG_PROC);
FunctionCall2Coll(procinfo,
index->rd_indcollation[0],
PointerGetDatum(&in),
PointerGetDatum(&cache->config));
/* Get the information we need about each relevant datatype */
fillTypeDesc(&cache->attType, atttype);
fillTypeDesc(&cache->attPrefixType, cache->config.prefixType);
fillTypeDesc(&cache->attLabelType, cache->config.labelType);
/* Last, get the lastUsedPages data from the metapage */
metabuffer = ReadBuffer(index, SPGIST_METAPAGE_BLKNO);
LockBuffer(metabuffer, BUFFER_LOCK_SHARE);
metadata = SpGistPageGetMeta(BufferGetPage(metabuffer));
if (metadata->magicNumber != SPGIST_MAGIC_NUMBER)
elog(ERROR, "index \"%s\" is not an SP-GiST index",
RelationGetRelationName(index));
cache->lastUsedPages = metadata->lastUsedPages;
UnlockReleaseBuffer(metabuffer);
index->rd_amcache = (void *) cache;
}
else
{
/* assume it's up to date */
cache = (SpGistCache *) index->rd_amcache;
}
return cache;
}
/* Initialize SpGistState for working with the given index */
void
initSpGistState(SpGistState *state, Relation index)
{
Oid atttype;
spgConfigIn in;
SpGistCache *cache;
/* SPGiST doesn't support multi-column indexes */
Assert(index->rd_att->natts == 1);
/* Get cached static information about index */
cache = spgGetCache(index);
/*
* Get the actual data type of the indexed column from the index tupdesc.
* We pass this to the opclass config function so that polymorphic
* opclasses are possible.
*/
atttype = index->rd_att->attrs[0]->atttypid;
/* Get the config info for the opclass */
in.attType = atttype;
memset(&state->config, 0, sizeof(state->config));
FunctionCall2Coll(index_getprocinfo(index, 1, SPGIST_CONFIG_PROC),
index->rd_indcollation[0],
PointerGetDatum(&in),
PointerGetDatum(&state->config));
/* Get the information we need about each relevant datatype */
fillTypeDesc(&state->attType, atttype);
fillTypeDesc(&state->attPrefixType, state->config.prefixType);
fillTypeDesc(&state->attLabelType, state->config.labelType);
/* Get lookup info for opclass support procs */
fmgr_info_copy(&(state->chooseFn),
index_getprocinfo(index, 1, SPGIST_CHOOSE_PROC),
CurrentMemoryContext);
fmgr_info_copy(&(state->picksplitFn),
index_getprocinfo(index, 1, SPGIST_PICKSPLIT_PROC),
CurrentMemoryContext);
fmgr_info_copy(&(state->innerConsistentFn),
index_getprocinfo(index, 1, SPGIST_INNER_CONSISTENT_PROC),
CurrentMemoryContext);
fmgr_info_copy(&(state->leafConsistentFn),
index_getprocinfo(index, 1, SPGIST_LEAF_CONSISTENT_PROC),
CurrentMemoryContext);
state->config = cache->config;
state->attType = cache->attType;
state->attPrefixType = cache->attPrefixType;
state->attLabelType = cache->attLabelType;
/* Make workspace for constructing dead tuples */
state->deadTupleStorage = palloc0(SGDTSIZE);
@ -86,6 +123,7 @@ initSpGistState(SpGistState *state, Relation index)
/* Set XID to use in redirection tuples */
state->myXid = GetTopTransactionIdIfAny();
/* Assume we're not in an index build (spgbuild will override) */
state->isBuild = false;
}
@ -153,46 +191,6 @@ SpGistNewBuffer(Relation index)
return buffer;
}
/*
* Fetch local cache of lastUsedPages info, initializing it from the metapage
* if necessary
*/
static SpGistCache *
spgGetCache(Relation index)
{
SpGistCache *cache;
if (index->rd_amcache == NULL)
{
Buffer metabuffer;
SpGistMetaPageData *metadata;
cache = MemoryContextAlloc(index->rd_indexcxt,
sizeof(SpGistCache));
metabuffer = ReadBuffer(index, SPGIST_METAPAGE_BLKNO);
LockBuffer(metabuffer, BUFFER_LOCK_SHARE);
metadata = SpGistPageGetMeta(BufferGetPage(metabuffer));
if (metadata->magicNumber != SPGIST_MAGIC_NUMBER)
elog(ERROR, "index \"%s\" is not an SP-GiST index",
RelationGetRelationName(index));
*cache = metadata->lastUsedPages;
UnlockReleaseBuffer(metabuffer);
index->rd_amcache = cache;
}
else
{
cache = (SpGistCache *) index->rd_amcache;
}
return cache;
}
/*
* Update index metapage's lastUsedPages info from local cache, if possible
*
@ -215,7 +213,7 @@ SpGistUpdateMetaPage(Relation index)
if (ConditionalLockBuffer(metabuffer))
{
metadata = SpGistPageGetMeta(BufferGetPage(metabuffer));
metadata->lastUsedPages = *cache;
metadata->lastUsedPages = cache->lastUsedPages;
MarkBufferDirty(metabuffer);
UnlockReleaseBuffer(metabuffer);
@ -229,8 +227,8 @@ SpGistUpdateMetaPage(Relation index)
/* Macro to select proper element of lastUsedPages cache depending on flags */
#define GET_LUP(c, f) (((f) & GBUF_LEAF) ? \
&(c)->leafPage : \
&(c)->innerPage[(f) & GBUF_PARITY_MASK])
&(c)->lastUsedPages.leafPage : \
&(c)->lastUsedPages.innerPage[(f) & GBUF_PARITY_MASK])
/*
* Allocate and initialize a new buffer of the type and parity specified by
@ -282,8 +280,8 @@ allocNewBuffer(Relation index, int flags)
else
{
/* Page has wrong parity, record it in cache and try again */
cache->innerPage[blkParity].blkno = blkno;
cache->innerPage[blkParity].freeSpace =
cache->lastUsedPages.innerPage[blkParity].blkno = blkno;
cache->lastUsedPages.innerPage[blkParity].freeSpace =
PageGetExactFreeSpace(BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
}