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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2005-06-13 23:14:49 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2005-06-13 23:14:49 +0000 |
| commit | c186c93148fdfa5a39972331318eda5318ff5eba (patch) | |
| tree | 31195d72e9b44d701eaa9018e498145f3d46f929 /src/backend/access/nbtree/nbtutils.c | |
| parent | 077811605e07212139c3df503fdaa081690635ca (diff) | |
| download | postgresql-c186c93148fdfa5a39972331318eda5318ff5eba.tar.gz postgresql-c186c93148fdfa5a39972331318eda5318ff5eba.zip | |
Change the planner to allow indexscan qualification clauses to use
nonconsecutive columns of a multicolumn index, as per discussion around
mid-May (pghackers thread "Best way to scan on-disk bitmaps"). This
turns out to require only minimal changes in btree, and so far as I can
see none at all in GiST. btcostestimate did need some work, but its
original assumption that index selectivity == heap selectivity was
quite bogus even before this.
Diffstat (limited to 'src/backend/access/nbtree/nbtutils.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtutils.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c index 96a3f05a5d6..9a5f8d7ac90 100644 --- a/src/backend/access/nbtree/nbtutils.c +++ b/src/backend/access/nbtree/nbtutils.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.62 2004/12/31 21:59:22 pgsql Exp $ + * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.63 2005/06/13 23:14:48 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -190,7 +190,9 @@ _bt_formitem(IndexTuple itup) * matched to continue the scan. In general, numberOfRequiredKeys is equal * to the number of keys for leading attributes with "=" keys, plus the * key(s) for the first non "=" attribute, which can be seen to be correct - * by considering the above example. + * by considering the above example. Note in particular that if there are no + * keys for a given attribute, the keys for subsequent attributes can never + * be required; for instance "WHERE y = 4" requires a full-index scan. * * If possible, redundant keys are eliminated: we keep only the tightest * >/>= bound and the tightest </<= bound, and if there's an = key then @@ -248,8 +250,8 @@ _bt_preprocess_keys(IndexScanDesc scan) outkeys = so->keyData; cur = &inkeys[0]; /* we check that input keys are correctly ordered */ - if (cur->sk_attno != 1) - elog(ERROR, "key(s) for attribute 1 missed"); + if (cur->sk_attno < 1) + elog(ERROR, "btree index keys must be ordered by attribute"); /* We can short-circuit most of the work if there's just one key */ if (numberOfKeys == 1) @@ -270,7 +272,8 @@ _bt_preprocess_keys(IndexScanDesc scan) } memcpy(outkeys, inkeys, sizeof(ScanKeyData)); so->numberOfKeys = 1; - so->numberOfRequiredKeys = 1; + if (cur->sk_attno == 1) + so->numberOfRequiredKeys = 1; return; } @@ -324,8 +327,8 @@ _bt_preprocess_keys(IndexScanDesc scan) int priorNumberOfEqualCols = numberOfEqualCols; /* check input keys are correctly ordered */ - if (i < numberOfKeys && cur->sk_attno != attno + 1) - elog(ERROR, "key(s) for attribute %d missed", attno + 1); + if (i < numberOfKeys && cur->sk_attno < attno) + elog(ERROR, "btree index keys must be ordered by attribute"); /* * If = has been specified, no other key will be used. In case |