Replace simple constant pg_am.amcanreturn with an AM support function.
The need for this was debated when we put in the index-only-scan feature, but at the time we had no near-term expectation of having AMs that could support such scans for only some indexes; so we kept it simple. However, the SP-GiST AM forces the issue, so let's fix it. This patch only installs the new API; no behavior actually changes.
This commit is contained in:
Tom Lane
parent
19d2231718
commit
3695a55513
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@ -481,13 +481,6 @@
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<entry>Does the access method support multicolumn indexes?</entry>
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</row>
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<row>
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<entry><structfield>amcanreturn</structfield></entry>
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<entry><type>bool</type></entry>
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<entry></entry>
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<entry>Can the access method return the contents of index entries?</entry>
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</row>
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<row>
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<entry><structfield>amoptionalkey</structfield></entry>
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<entry><type>bool</type></entry>
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@ -622,6 +615,14 @@
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<entry>Post-<command>VACUUM</command> cleanup function</entry>
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</row>
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<row>
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<entry><structfield>amcanreturn</structfield></entry>
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<entry><type>regproc</type></entry>
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<entry><literal><link linkend="catalog-pg-proc"><structname>pg_proc</structname></link>.oid</literal></entry>
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<entry>Function to check whether index supports index-only scans,
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or zero if none</entry>
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</row>
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<row>
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<entry><structfield>amcostestimate</structfield></entry>
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<entry><type>regproc</type></entry>
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@ -134,11 +134,6 @@
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<structfield>amsearchnulls</structfield>, indicating that it supports
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<literal>IS NULL</> and <literal>IS NOT NULL</> clauses as search
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conditions.
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An index method can also set <structfield>amcanreturn</structfield>,
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indicating that it can support <firstterm>index-only scans</> by returning
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the indexed column values for an index entry in the form of an IndexTuple.
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(An example of an index AM that cannot do this is hash, which stores only
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the hash values not the original data.)
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</para>
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</sect1>
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@ -278,6 +273,19 @@ amvacuumcleanup (IndexVacuumInfo *info,
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<para>
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<programlisting>
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bool
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amcanreturn (Relation indexRelation);
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</programlisting>
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Check whether the index can support <firstterm>index-only scans</> by
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returning the indexed column values for an index entry in the form of an
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IndexTuple. Return TRUE if so, else FALSE. If the index AM can never
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support index-only scans (an example is hash, which stores only
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the hash values not the original data), it is sufficient to set its
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<structfield>amcanreturn</> field to zero in <structname>pg_am</>.
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</para>
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<para>
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<programlisting>
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void
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amcostestimate (PlannerInfo *root,
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IndexOptInfo *index,
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@ -391,9 +399,9 @@ amgettuple (IndexScanDesc scan,
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</para>
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<para>
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If the access method supports index-only scans (i.e.,
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<structfield>amcanreturn</structfield> is TRUE in its <structname>pg_am</>
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row), then on success it must also check
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If the index supports index-only scans (i.e.,
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<function>amcanreturn</function> returns TRUE for it),
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then on success the AM must also check
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<literal>scan->xs_want_itup</>, and if that is true it must return
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the original indexed data for the index entry, in the form of an
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<structname>IndexTuple</> pointer stored at <literal>scan->xs_itup</>,
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@ -26,6 +26,7 @@
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* index_getbitmap - get all tuples from a scan
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* index_bulk_delete - bulk deletion of index tuples
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* index_vacuum_cleanup - post-deletion cleanup of an index
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* index_can_return - does index support index-only scans?
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* index_getprocid - get a support procedure OID
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* index_getprocinfo - get a support procedure's lookup info
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*
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@ -711,6 +712,27 @@ index_vacuum_cleanup(IndexVacuumInfo *info,
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return result;
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}
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/* ----------------
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* index_can_return - does index support index-only scans?
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* ----------------
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*/
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bool
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index_can_return(Relation indexRelation)
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{
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FmgrInfo *procedure;
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RELATION_CHECKS;
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/* amcanreturn is optional; assume FALSE if not provided by AM */
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if (!RegProcedureIsValid(indexRelation->rd_am->amcanreturn))
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return false;
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GET_REL_PROCEDURE(amcanreturn);
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return DatumGetBool(FunctionCall1(procedure,
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PointerGetDatum(indexRelation)));
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}
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/* ----------------
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* index_getprocid
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*
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@ -1091,3 +1091,14 @@ restart:
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goto restart;
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}
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}
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/*
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* btcanreturn() -- Check whether btree indexes support index-only scans.
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*
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* btrees always do, so this is trivial.
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*/
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Datum
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btcanreturn(PG_FUNCTION_ARGS)
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{
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PG_RETURN_BOOL(true);
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}
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@ -559,3 +559,10 @@ spggettuple(PG_FUNCTION_ARGS)
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PG_RETURN_BOOL(false);
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}
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Datum
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spgcanreturn(PG_FUNCTION_ARGS)
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{
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/* Not implemented yet */
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PG_RETURN_BOOL(false);
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}
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@ -1075,10 +1075,10 @@ check_index_only(RelOptInfo *rel, IndexOptInfo *index)
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ListCell *lc;
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int i;
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/* Index-only scans must be enabled, and AM must be capable of it */
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/* Index-only scans must be enabled, and index must be capable of them */
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if (!enable_indexonlyscan)
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return false;
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if (!index->amcanreturn)
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if (!index->canreturn)
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return false;
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/*
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@ -212,8 +212,8 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
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info->relam = indexRelation->rd_rel->relam;
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info->amcostestimate = indexRelation->rd_am->amcostestimate;
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info->canreturn = index_can_return(indexRelation);
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info->amcanorderbyop = indexRelation->rd_am->amcanorderbyop;
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info->amcanreturn = indexRelation->rd_am->amcanreturn;
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info->amoptionalkey = indexRelation->rd_am->amoptionalkey;
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info->amsearcharray = indexRelation->rd_am->amsearcharray;
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info->amsearchnulls = indexRelation->rd_am->amsearchnulls;
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@ -156,6 +156,7 @@ extern IndexBulkDeleteResult *index_bulk_delete(IndexVacuumInfo *info,
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void *callback_state);
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extern IndexBulkDeleteResult *index_vacuum_cleanup(IndexVacuumInfo *info,
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IndexBulkDeleteResult *stats);
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extern bool index_can_return(Relation indexRelation);
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extern RegProcedure index_getprocid(Relation irel, AttrNumber attnum,
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uint16 procnum);
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extern FmgrInfo *index_getprocinfo(Relation irel, AttrNumber attnum,
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@ -607,6 +607,7 @@ extern Datum btmarkpos(PG_FUNCTION_ARGS);
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extern Datum btrestrpos(PG_FUNCTION_ARGS);
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extern Datum btbulkdelete(PG_FUNCTION_ARGS);
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extern Datum btvacuumcleanup(PG_FUNCTION_ARGS);
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extern Datum btcanreturn(PG_FUNCTION_ARGS);
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extern Datum btoptions(PG_FUNCTION_ARGS);
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/*
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@ -182,6 +182,7 @@ extern Datum spgmarkpos(PG_FUNCTION_ARGS);
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extern Datum spgrestrpos(PG_FUNCTION_ARGS);
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extern Datum spggetbitmap(PG_FUNCTION_ARGS);
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extern Datum spggettuple(PG_FUNCTION_ARGS);
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extern Datum spgcanreturn(PG_FUNCTION_ARGS);
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/* spgutils.c */
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extern Datum spgoptions(PG_FUNCTION_ARGS);
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@ -53,6 +53,6 @@
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*/
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/* yyyymmddN */
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#define CATALOG_VERSION_NO 201112172
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#define CATALOG_VERSION_NO 201112181
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#endif
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@ -45,7 +45,6 @@ CATALOG(pg_am,2601)
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bool amcanbackward; /* does AM support backward scan? */
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bool amcanunique; /* does AM support UNIQUE indexes? */
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bool amcanmulticol; /* does AM support multi-column indexes? */
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bool amcanreturn; /* can AM return IndexTuples? */
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bool amoptionalkey; /* can query omit key for the first column? */
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bool amsearcharray; /* can AM handle ScalarArrayOpExpr quals? */
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bool amsearchnulls; /* can AM search for NULL/NOT NULL entries? */
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@ -65,6 +64,7 @@ CATALOG(pg_am,2601)
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regproc ambuildempty; /* "build empty index" function */
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regproc ambulkdelete; /* bulk-delete function */
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regproc amvacuumcleanup; /* post-VACUUM cleanup function */
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regproc amcanreturn; /* can indexscan return IndexTuples? */
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regproc amcostestimate; /* estimate cost of an indexscan */
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regproc amoptions; /* parse AM-specific parameters */
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} FormData_pg_am;
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@ -89,26 +89,26 @@ typedef FormData_pg_am *Form_pg_am;
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#define Anum_pg_am_amcanbackward 6
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#define Anum_pg_am_amcanunique 7
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#define Anum_pg_am_amcanmulticol 8
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#define Anum_pg_am_amcanreturn 9
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#define Anum_pg_am_amoptionalkey 10
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#define Anum_pg_am_amsearcharray 11
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#define Anum_pg_am_amsearchnulls 12
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#define Anum_pg_am_amstorage 13
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#define Anum_pg_am_amclusterable 14
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#define Anum_pg_am_ampredlocks 15
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#define Anum_pg_am_amkeytype 16
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#define Anum_pg_am_aminsert 17
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#define Anum_pg_am_ambeginscan 18
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#define Anum_pg_am_amgettuple 19
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#define Anum_pg_am_amgetbitmap 20
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#define Anum_pg_am_amrescan 21
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#define Anum_pg_am_amendscan 22
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#define Anum_pg_am_ammarkpos 23
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#define Anum_pg_am_amrestrpos 24
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#define Anum_pg_am_ambuild 25
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#define Anum_pg_am_ambuildempty 26
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#define Anum_pg_am_ambulkdelete 27
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#define Anum_pg_am_amvacuumcleanup 28
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#define Anum_pg_am_amoptionalkey 9
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#define Anum_pg_am_amsearcharray 10
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#define Anum_pg_am_amsearchnulls 11
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#define Anum_pg_am_amstorage 12
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#define Anum_pg_am_amclusterable 13
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#define Anum_pg_am_ampredlocks 14
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#define Anum_pg_am_amkeytype 15
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#define Anum_pg_am_aminsert 16
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#define Anum_pg_am_ambeginscan 17
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#define Anum_pg_am_amgettuple 18
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#define Anum_pg_am_amgetbitmap 19
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#define Anum_pg_am_amrescan 20
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#define Anum_pg_am_amendscan 21
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#define Anum_pg_am_ammarkpos 22
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#define Anum_pg_am_amrestrpos 23
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#define Anum_pg_am_ambuild 24
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#define Anum_pg_am_ambuildempty 25
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#define Anum_pg_am_ambulkdelete 26
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#define Anum_pg_am_amvacuumcleanup 27
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#define Anum_pg_am_amcanreturn 28
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#define Anum_pg_am_amcostestimate 29
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#define Anum_pg_am_amoptions 30
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@ -117,19 +117,19 @@ typedef FormData_pg_am *Form_pg_am;
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* ----------------
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*/
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DATA(insert OID = 403 ( btree 5 2 t f t t t t t t t f t t 0 btinsert btbeginscan btgettuple btgetbitmap btrescan btendscan btmarkpos btrestrpos btbuild btbuildempty btbulkdelete btvacuumcleanup btcostestimate btoptions ));
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DATA(insert OID = 403 ( btree 5 2 t f t t t t t t f t t 0 btinsert btbeginscan btgettuple btgetbitmap btrescan btendscan btmarkpos btrestrpos btbuild btbuildempty btbulkdelete btvacuumcleanup btcanreturn btcostestimate btoptions ));
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DESCR("b-tree index access method");
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#define BTREE_AM_OID 403
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DATA(insert OID = 405 ( hash 1 1 f f t f f f f f f f f f 23 hashinsert hashbeginscan hashgettuple hashgetbitmap hashrescan hashendscan hashmarkpos hashrestrpos hashbuild hashbuildempty hashbulkdelete hashvacuumcleanup hashcostestimate hashoptions ));
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DATA(insert OID = 405 ( hash 1 1 f f t f f f f f f f f 23 hashinsert hashbeginscan hashgettuple hashgetbitmap hashrescan hashendscan hashmarkpos hashrestrpos hashbuild hashbuildempty hashbulkdelete hashvacuumcleanup - hashcostestimate hashoptions ));
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DESCR("hash index access method");
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#define HASH_AM_OID 405
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DATA(insert OID = 783 ( gist 0 8 f t f f t f t f t t t f 0 gistinsert gistbeginscan gistgettuple gistgetbitmap gistrescan gistendscan gistmarkpos gistrestrpos gistbuild gistbuildempty gistbulkdelete gistvacuumcleanup gistcostestimate gistoptions ));
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DATA(insert OID = 783 ( gist 0 8 f t f f t t f t t t f 0 gistinsert gistbeginscan gistgettuple gistgetbitmap gistrescan gistendscan gistmarkpos gistrestrpos gistbuild gistbuildempty gistbulkdelete gistvacuumcleanup - gistcostestimate gistoptions ));
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DESCR("GiST index access method");
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#define GIST_AM_OID 783
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DATA(insert OID = 2742 ( gin 0 5 f f f f t f t f f t f f 0 gininsert ginbeginscan - gingetbitmap ginrescan ginendscan ginmarkpos ginrestrpos ginbuild ginbuildempty ginbulkdelete ginvacuumcleanup gincostestimate ginoptions ));
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DATA(insert OID = 2742 ( gin 0 5 f f f f t t f f t f f 0 gininsert ginbeginscan - gingetbitmap ginrescan ginendscan ginmarkpos ginrestrpos ginbuild ginbuildempty ginbulkdelete ginvacuumcleanup - gincostestimate ginoptions ));
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DESCR("GIN index access method");
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#define GIN_AM_OID 2742
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DATA(insert OID = 4000 ( spgist 0 5 f f f f f f f f f f f f 0 spginsert spgbeginscan spggettuple spggetbitmap spgrescan spgendscan spgmarkpos spgrestrpos spgbuild spgbuildempty spgbulkdelete spgvacuumcleanup spgcostestimate spgoptions ));
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DATA(insert OID = 4000 ( spgist 0 5 f f f f f f f f f f f 0 spginsert spgbeginscan spggettuple spggetbitmap spgrescan spgendscan spgmarkpos spgrestrpos spgbuild spgbuildempty spgbulkdelete spgvacuumcleanup spgcanreturn spgcostestimate spgoptions ));
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DESCR("SP-GiST index access method");
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#define SPGIST_AM_OID 4000
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@ -546,6 +546,8 @@ DATA(insert OID = 332 ( btbulkdelete PGNSP PGUID 12 1 0 0 0 f f f t f v 4 0
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DESCR("btree(internal)");
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DATA(insert OID = 972 ( btvacuumcleanup PGNSP PGUID 12 1 0 0 0 f f f t f v 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ btvacuumcleanup _null_ _null_ _null_ ));
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DESCR("btree(internal)");
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DATA(insert OID = 276 ( btcanreturn PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 16 "2281" _null_ _null_ _null_ _null_ btcanreturn _null_ _null_ _null_ ));
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DESCR("btree(internal)");
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DATA(insert OID = 1268 ( btcostestimate PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ btcostestimate _null_ _null_ _null_ ));
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DESCR("btree(internal)");
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DATA(insert OID = 2785 ( btoptions PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_ btoptions _null_ _null_ _null_ ));
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@ -4506,6 +4508,8 @@ DATA(insert OID = 4011 ( spgbulkdelete PGNSP PGUID 12 1 0 0 0 f f f t f v 4
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DESCR("spgist(internal)");
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DATA(insert OID = 4012 ( spgvacuumcleanup PGNSP PGUID 12 1 0 0 0 f f f t f v 2 0 2281 "2281 2281" _null_ _null_ _null_ _null_ spgvacuumcleanup _null_ _null_ _null_ ));
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DESCR("spgist(internal)");
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DATA(insert OID = 4032 ( spgcanreturn PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 16 "2281" _null_ _null_ _null_ _null_ spgcanreturn _null_ _null_ _null_ ));
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DESCR("spgist(internal)");
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DATA(insert OID = 4013 ( spgcostestimate PGNSP PGUID 12 1 0 0 0 f f f t f v 9 0 2278 "2281 2281 2281 2281 2281 2281 2281 2281 2281" _null_ _null_ _null_ _null_ spgcostestimate _null_ _null_ _null_ ));
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DESCR("spgist(internal)");
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DATA(insert OID = 4014 ( spgoptions PGNSP PGUID 12 1 0 0 0 f f f t f s 2 0 17 "1009 16" _null_ _null_ _null_ _null_ spgoptions _null_ _null_ _null_ ));
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@ -490,8 +490,8 @@ typedef struct IndexOptInfo
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bool unique; /* true if a unique index */
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bool immediate; /* is uniqueness enforced immediately? */
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bool hypothetical; /* true if index doesn't really exist */
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bool canreturn; /* can index return IndexTuples? */
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bool amcanorderbyop; /* does AM support order by operator result? */
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bool amcanreturn; /* can AM return IndexTuples? */
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bool amoptionalkey; /* can query omit key for the first column? */
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bool amsearcharray; /* can AM handle ScalarArrayOpExpr quals? */
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bool amsearchnulls; /* can AM search for NULL/NOT NULL entries? */
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@ -64,6 +64,7 @@ typedef struct RelationAmInfo
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FmgrInfo ambuildempty;
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FmgrInfo ambulkdelete;
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FmgrInfo amvacuumcleanup;
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FmgrInfo amcanreturn;
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FmgrInfo amcostestimate;
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FmgrInfo amoptions;
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} RelationAmInfo;
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