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Restructure index access method API to hide most of it at the C level.
This patch reduces pg_am to just two columns, a name and a handler function. All the data formerly obtained from pg_am is now provided in a C struct returned by the handler function. This is similar to the designs we've adopted for FDWs and tablesample methods. There are multiple advantages. For one, the index AM's support functions are now simple C functions, making them faster to call and much less error-prone, since the C compiler can now check function signatures. For another, this will make it far more practical to define index access methods in installable extensions. A disadvantage is that SQL-level code can no longer see attributes of index AMs; in particular, some of the crosschecks in the opr_sanity regression test are no longer possible from SQL. We've addressed that by adding a facility for the index AM to perform such checks instead. (Much more could be done in that line, but for now we're content if the amvalidate functions more or less replace what opr_sanity used to do.) We might also want to expose some sort of reporting functionality, but this patch doesn't do that. Alexander Korotkov, reviewed by Petr Jelínek, and rather heavily editorialized on by me.
This commit is contained in:
Tom Lane
204
src/backend/access/nbtree/nbtvalidate.c
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204
src/backend/access/nbtree/nbtvalidate.c
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/*-------------------------------------------------------------------------
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*
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* nbtvalidate.c
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* Opclass validator for btree.
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*
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* Portions Copyright (c) 1996-2016, 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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* src/backend/access/nbtree/nbtvalidate.c
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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/htup_details.h"
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#include "access/nbtree.h"
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#include "catalog/pg_amop.h"
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#include "catalog/pg_amproc.h"
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#include "catalog/pg_opclass.h"
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#include "utils/builtins.h"
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#include "utils/catcache.h"
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#include "utils/syscache.h"
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/*
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* Validator for a btree opclass.
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*
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* Some of the checks done here cover the whole opfamily, and therefore are
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* redundant when checking each opclass in a family. But they don't run long
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* enough to be much of a problem, so we accept the duplication rather than
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* complicate the amvalidate API.
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*/
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bool
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btvalidate(Oid opclassoid)
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{
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HeapTuple classtup;
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Form_pg_opclass classform;
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Oid opfamilyoid;
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Oid opcintype;
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int numclassops;
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int32 classfuncbits;
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CatCList *proclist,
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*oprlist;
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Oid lastlefttype,
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lastrighttype;
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int numOps;
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int i,
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j;
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/* Fetch opclass information */
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classtup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclassoid));
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if (!HeapTupleIsValid(classtup))
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elog(ERROR, "cache lookup failed for operator class %u", opclassoid);
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classform = (Form_pg_opclass) GETSTRUCT(classtup);
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opfamilyoid = classform->opcfamily;
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opcintype = classform->opcintype;
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ReleaseSysCache(classtup);
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/* Fetch all operators and support functions of the opfamily */
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oprlist = SearchSysCacheList1(AMOPSTRATEGY, ObjectIdGetDatum(opfamilyoid));
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proclist = SearchSysCacheList1(AMPROCNUM, ObjectIdGetDatum(opfamilyoid));
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/* We rely on the oprlist to be ordered */
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if (!oprlist->ordered)
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elog(ERROR, "cannot validate btree opclass without ordered data");
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/* We'll track the ops and functions belonging to the named opclass */
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numclassops = 0;
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classfuncbits = 0;
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/* Check support functions */
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for (i = 0; i < proclist->n_members; i++)
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{
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HeapTuple proctup = &proclist->members[i]->tuple;
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Form_pg_amproc procform = (Form_pg_amproc) GETSTRUCT(proctup);
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/* Check that only allowed procedure numbers exist */
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if (procform->amprocnum != BTORDER_PROC &&
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procform->amprocnum != BTSORTSUPPORT_PROC)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opfamily %u contains invalid support number %d for procedure %u",
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opfamilyoid,
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procform->amprocnum, procform->amproc)));
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/* Remember functions that are specifically for the named opclass */
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if (procform->amproclefttype == opcintype &&
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procform->amprocrighttype == opcintype)
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classfuncbits |= (1 << procform->amprocnum);
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}
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/* Check operators */
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lastlefttype = lastrighttype = InvalidOid;
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numOps = 0;
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for (i = 0; i < oprlist->n_members; i++)
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{
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HeapTuple oprtup = &oprlist->members[i]->tuple;
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Form_pg_amop oprform = (Form_pg_amop) GETSTRUCT(oprtup);
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/* Check that only allowed strategy numbers exist */
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if (oprform->amopstrategy < 1 ||
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oprform->amopstrategy > BTMaxStrategyNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opfamily %u contains invalid strategy number %d for operator %u",
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opfamilyoid,
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oprform->amopstrategy, oprform->amopopr)));
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/*
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* Check that we have all strategies for each supported datatype
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* combination. This is easy since the list will be sorted in
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* datatype order and there can't be duplicate strategy numbers.
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*/
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if (oprform->amoplefttype == lastlefttype &&
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oprform->amoprighttype == lastrighttype)
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numOps++;
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else
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{
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/* reached a group boundary, so check ... */
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if (numOps > 0 && numOps != BTMaxStrategyNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opfamily %u has a partial set of operators for datatypes %s and %s",
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opfamilyoid,
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format_type_be(lastlefttype),
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format_type_be(lastrighttype))));
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/* ... and reset for new group */
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lastlefttype = oprform->amoplefttype;
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lastrighttype = oprform->amoprighttype;
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numOps = 1;
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}
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/*
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* There should be a relevant support function for each operator, but
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* we only need to check this once per pair of datatypes.
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*/
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if (numOps == 1)
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{
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bool found = false;
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for (j = 0; j < proclist->n_members; j++)
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{
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HeapTuple proctup = &proclist->members[j]->tuple;
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Form_pg_amproc procform = (Form_pg_amproc) GETSTRUCT(proctup);
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if (procform->amprocnum == BTORDER_PROC &&
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procform->amproclefttype == oprform->amoplefttype &&
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procform->amprocrighttype == oprform->amoprighttype)
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{
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found = true;
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break;
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}
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}
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if (!found)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opfamily %u lacks support function for operator %u",
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opfamilyoid, oprform->amopopr)));
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}
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/* btree doesn't support ORDER BY operators */
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if (oprform->amoppurpose != AMOP_SEARCH ||
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OidIsValid(oprform->amopsortfamily))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opfamily %u contains invalid ORDER BY specification for operator %u",
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opfamilyoid, oprform->amopopr)));
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/* Count operators that are specifically for the named opclass */
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if (oprform->amoplefttype == opcintype &&
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oprform->amoprighttype == opcintype)
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numclassops++;
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}
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/* don't forget to check the last batch of operators for completeness */
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if (numOps > 0 && numOps != BTMaxStrategyNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opfamily %u has a partial set of operators for datatypes %s and %s",
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opfamilyoid,
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format_type_be(lastlefttype),
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format_type_be(lastrighttype))));
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/* Check that the named opclass is complete */
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if (numclassops != BTMaxStrategyNumber)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opclass %u is missing operator(s)",
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opclassoid)));
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if ((classfuncbits & (1 << BTORDER_PROC)) == 0)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
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errmsg("btree opclass %u is missing required support function",
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opclassoid)));
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ReleaseCatCacheList(proclist);
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ReleaseCatCacheList(oprlist);
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return true;
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}
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