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Restructure index access method API to hide most of it at the C level.

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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
2016-01-17 19:36:59 -05:00
parent 8d290c8ec6
commit 65c5fcd353
93 changed files with 2493 additions and 1924 deletions
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157
src/backend/access/hash/hashvalidate.c Normal file
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/*-------------------------------------------------------------------------
*
* hashvalidate.c
* Opclass validator for hash.
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/access/hash/hashvalidate.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/hash.h"
#include "access/htup_details.h"
#include "catalog/pg_amop.h"
#include "catalog/pg_amproc.h"
#include "catalog/pg_opclass.h"
#include "utils/builtins.h"
#include "utils/catcache.h"
#include "utils/syscache.h"
/*
* Validator for a hash opclass.
*
* Some of the checks done here cover the whole opfamily, and therefore are
* redundant when checking each opclass in a family. But they don't run long
* enough to be much of a problem, so we accept the duplication rather than
* complicate the amvalidate API.
*
* Some of the code here relies on the fact that hash has only one operator
* strategy and support function; we don't have to check for incomplete sets.
*/
bool
hashvalidate(Oid opclassoid)
{
HeapTuple classtup;
Form_pg_opclass classform;
Oid opfamilyoid;
Oid opcintype;
int numclassops;
int32 classfuncbits;
CatCList *proclist,
*oprlist;
int i,
j;
/* Fetch opclass information */
classtup = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclassoid));
if (!HeapTupleIsValid(classtup))
elog(ERROR, "cache lookup failed for operator class %u", opclassoid);
classform = (Form_pg_opclass) GETSTRUCT(classtup);
opfamilyoid = classform->opcfamily;
opcintype = classform->opcintype;
ReleaseSysCache(classtup);
/* Fetch all operators and support functions of the opfamily */
oprlist = SearchSysCacheList1(AMOPSTRATEGY, ObjectIdGetDatum(opfamilyoid));
proclist = SearchSysCacheList1(AMPROCNUM, ObjectIdGetDatum(opfamilyoid));
/* We'll track the ops and functions belonging to the named opclass */
numclassops = 0;
classfuncbits = 0;
/* Check support functions */
for (i = 0; i < proclist->n_members; i++)
{
HeapTuple proctup = &proclist->members[i]->tuple;
Form_pg_amproc procform = (Form_pg_amproc) GETSTRUCT(proctup);
/* Check that only allowed procedure numbers exist */
if (procform->amprocnum != HASHPROC)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash opfamily %u contains invalid support number %d for procedure %u",
opfamilyoid,
procform->amprocnum, procform->amproc)));
/* Remember functions that are specifically for the named opclass */
if (procform->amproclefttype == opcintype &&
procform->amprocrighttype == opcintype)
classfuncbits |= (1 << procform->amprocnum);
}
/* Check operators */
for (i = 0; i < oprlist->n_members; i++)
{
HeapTuple oprtup = &oprlist->members[i]->tuple;
Form_pg_amop oprform = (Form_pg_amop) GETSTRUCT(oprtup);
bool leftFound = false,
rightFound = false;
/* Check that only allowed strategy numbers exist */
if (oprform->amopstrategy < 1 ||
oprform->amopstrategy > HTMaxStrategyNumber)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash opfamily %u contains invalid strategy number %d for operator %u",
opfamilyoid,
oprform->amopstrategy, oprform->amopopr)));
/*
* There should be relevant hash procedures for each operator
*/
for (j = 0; j < proclist->n_members; j++)
{
HeapTuple proctup = &proclist->members[j]->tuple;
Form_pg_amproc procform = (Form_pg_amproc) GETSTRUCT(proctup);
if (procform->amproclefttype == oprform->amoplefttype)
leftFound = true;
if (procform->amproclefttype == oprform->amoprighttype)
rightFound = true;
}
if (!leftFound || !rightFound)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash opfamily %u lacks support function for operator %u",
opfamilyoid, oprform->amopopr)));
/* hash doesn't support ORDER BY operators */
if (oprform->amoppurpose != AMOP_SEARCH ||
OidIsValid(oprform->amopsortfamily))
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash opfamily %u contains invalid ORDER BY specification for operator %u",
opfamilyoid, oprform->amopopr)));
/* Count operators that are specifically for the named opclass */
if (oprform->amoplefttype == opcintype &&
oprform->amoprighttype == opcintype)
numclassops++;
}
/* Check that the named opclass is complete */
if (numclassops != HTMaxStrategyNumber)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash opclass %u is missing operator(s)",
opclassoid)));
if ((classfuncbits & (1 << HASHPROC)) == 0)
ereport(ERROR,
(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
errmsg("hash opclass %u is missing required support function",
opclassoid)));
ReleaseCatCacheList(proclist);
ReleaseCatCacheList(oprlist);
return true;
}