479 lines
15 KiB
C++
479 lines
15 KiB
C++
/*
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* contrib/pgstattuple/pgstattuple.c
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*
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* Copyright (c) 2001,2002 Tatsuo Ishii
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*
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* Permission to use, copy, modify, and distribute this software and
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* its documentation for any purpose, without fee, and without a
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* written agreement is hereby granted, provided that the above
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* copyright notice and this paragraph and the following two
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* paragraphs appear in all copies.
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*
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
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* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
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* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
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* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
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* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
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* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
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*/
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#include "postgres.h"
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#include "knl/knl_variable.h"
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#include "access/gist_private.h"
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#include "access/hash.h"
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#include "access/nbtree.h"
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#include "access/relscan.h"
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#include "catalog/namespace.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "storage/buf/bufmgr.h"
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#include "storage/lmgr.h"
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#include "utils/builtins.h"
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PG_MODULE_MAGIC;
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PG_FUNCTION_INFO_V1(pgstattuple);
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PG_FUNCTION_INFO_V1(pgstattuplebyid);
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extern "C" Datum pgstattuple(PG_FUNCTION_ARGS);
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extern "C" Datum pgstattuplebyid(PG_FUNCTION_ARGS);
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/*
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* struct pgstattuple_type
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*
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* tuple_percent, dead_tuple_percent and free_percent are computable,
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* so not defined here.
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*/
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typedef struct pgstattuple_type {
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uint64 table_len;
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uint64 tuple_count;
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uint64 tuple_len;
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uint64 dead_tuple_count;
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uint64 dead_tuple_len;
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uint64 free_space; /* free/reusable space in bytes */
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} pgstattuple_type;
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typedef void (*pgstat_page)(pgstattuple_type*, Relation, BlockNumber, BufferAccessStrategy);
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static Datum build_pgstattuple_type(pgstattuple_type* stat, FunctionCallInfo fcinfo);
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static Datum pgstat_relation(Relation rel, FunctionCallInfo fcinfo);
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static Datum pgstat_heap(Relation rel, FunctionCallInfo fcinfo);
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static void pgstat_btree_page(pgstattuple_type* stat, Relation rel, BlockNumber blkno, BufferAccessStrategy bstrategy);
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static void pgstat_hash_page(pgstattuple_type* stat, Relation rel, BlockNumber blkno, BufferAccessStrategy bstrategy);
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static void pgstat_gist_page(pgstattuple_type* stat, Relation rel, BlockNumber blkno, BufferAccessStrategy bstrategy);
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static Datum pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn, FunctionCallInfo fcinfo);
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static void pgstat_index_page(pgstattuple_type* stat, Page page, OffsetNumber minoff, OffsetNumber maxoff);
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/*
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* build_pgstattuple_type -- build a pgstattuple_type tuple
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*/
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static Datum build_pgstattuple_type(pgstattuple_type* stat, FunctionCallInfo fcinfo)
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{
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#define NCOLUMNS 9
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#define NCHARS 32
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HeapTuple tuple;
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char* values[NCOLUMNS];
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char values_buf[NCOLUMNS][NCHARS];
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int i;
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double tuple_percent;
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double dead_tuple_percent;
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double free_percent; /* free/reusable space in % */
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TupleDesc tupdesc;
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AttInMetadata* attinmeta = NULL;
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/* Build a tuple descriptor for our result type */
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if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
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elog(ERROR, "return type must be a row type");
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/*
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* Generate attribute metadata needed later to produce tuples from raw C
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* strings
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*/
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attinmeta = TupleDescGetAttInMetadata(tupdesc);
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if (stat->table_len == 0) {
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tuple_percent = 0.0;
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dead_tuple_percent = 0.0;
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free_percent = 0.0;
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} else {
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tuple_percent = 100.0 * stat->tuple_len / stat->table_len;
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dead_tuple_percent = 100.0 * stat->dead_tuple_len / stat->table_len;
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free_percent = 100.0 * stat->free_space / stat->table_len;
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}
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/*
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* Prepare a values array for constructing the tuple. This should be an
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* array of C strings which will be processed later by the appropriate
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* "in" functions.
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*/
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for (i = 0; i < NCOLUMNS; i++)
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values[i] = values_buf[i];
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i = 0;
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snprintf(values[i++], NCHARS, INT64_FORMAT, stat->table_len);
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snprintf(values[i++], NCHARS, INT64_FORMAT, stat->tuple_count);
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snprintf(values[i++], NCHARS, INT64_FORMAT, stat->tuple_len);
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snprintf(values[i++], NCHARS, "%.2f", tuple_percent);
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snprintf(values[i++], NCHARS, INT64_FORMAT, stat->dead_tuple_count);
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snprintf(values[i++], NCHARS, INT64_FORMAT, stat->dead_tuple_len);
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snprintf(values[i++], NCHARS, "%.2f", dead_tuple_percent);
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snprintf(values[i++], NCHARS, INT64_FORMAT, stat->free_space);
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snprintf(values[i++], NCHARS, "%.2f", free_percent);
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/* build a tuple */
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tuple = BuildTupleFromCStrings(attinmeta, values);
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/* make the tuple into a datum */
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return HeapTupleGetDatum(tuple);
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}
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/* ----------
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* pgstattuple:
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* returns live/dead tuples info
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*
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* C FUNCTION definition
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* pgstattuple(text) returns pgstattuple_type
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* see pgstattuple.sql for pgstattuple_type
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* ----------
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*/
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Datum pgstattuple(PG_FUNCTION_ARGS)
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{
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text* relname = PG_GETARG_TEXT_P(0);
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RangeVar* relrv = NULL;
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Relation rel;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use pgstattuple functions"))));
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/* open relation */
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relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
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rel = relation_openrv(relrv, AccessShareLock);
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PG_RETURN_DATUM(pgstat_relation(rel, fcinfo));
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}
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Datum pgstattuplebyid(PG_FUNCTION_ARGS)
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{
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Oid relid = PG_GETARG_OID(0);
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Relation rel;
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if (!superuser())
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ereport(ERROR,
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(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be system admin to use pgstattuple functions"))));
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/* open relation */
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rel = relation_open(relid, AccessShareLock);
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PG_RETURN_DATUM(pgstat_relation(rel, fcinfo));
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}
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/*
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* pgstat_relation
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*/
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static Datum pgstat_relation(Relation rel, FunctionCallInfo fcinfo)
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{
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const char* err = NULL;
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/*
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* Reject attempts to read non-local temporary relations; we would be
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* likely to get wrong data since we have no visibility into the owning
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* session's local buffers.
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*/
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if (RELATION_IS_OTHER_TEMP(rel))
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions")));
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switch (rel->rd_rel->relkind) {
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case RELKIND_RELATION:
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case RELKIND_TOASTVALUE:
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case RELKIND_UNCATALOGED:
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case RELKIND_SEQUENCE:
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return pgstat_heap(rel, fcinfo);
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case RELKIND_INDEX:
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switch (rel->rd_rel->relam) {
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case BTREE_AM_OID:
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return pgstat_index(rel, BTREE_METAPAGE + 1, pgstat_btree_page, fcinfo);
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case HASH_AM_OID:
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return pgstat_index(rel, HASH_METAPAGE + 1, pgstat_hash_page, fcinfo);
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case GIST_AM_OID:
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return pgstat_index(rel, GIST_ROOT_BLKNO + 1, pgstat_gist_page, fcinfo);
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case GIN_AM_OID:
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err = "gin index";
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break;
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case SPGIST_AM_OID:
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err = "spgist index";
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break;
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default:
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err = "unknown index";
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break;
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}
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break;
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case RELKIND_VIEW:
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err = "view";
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break;
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case RELKIND_CONTQUERY:
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err = "contview";
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break;
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case RELKIND_COMPOSITE_TYPE:
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err = "composite type";
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break;
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case RELKIND_FOREIGN_TABLE:
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err = "foreign table";
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break;
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case RELKIND_STREAM:
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err = "stream";
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break;
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default:
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err = "unknown";
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break;
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}
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("\"%s\" (%s) is not supported", RelationGetRelationName(rel), err)));
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return 0; /* should not happen */
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}
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/*
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* pgstat_heap -- returns live/dead tuples info in a heap
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*/
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static Datum pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
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{
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HeapScanDesc scan;
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HeapTuple tuple;
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BlockNumber nblocks;
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BlockNumber block = 0; /* next block to count free space in */
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BlockNumber tupblock;
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Buffer buffer;
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pgstattuple_type stat = {0};
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BufferAccessStrategy bstrategy;
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/* Disable syncscan because we assume we scan from block zero upwards */
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scan = heap_beginscan_strat(rel, SnapshotAny, 0, NULL, true, false);
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nblocks = scan->rs_nblocks; /* # blocks to be scanned */
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/* prepare access strategy for this table */
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bstrategy = GetAccessStrategy(BAS_BULKREAD);
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scan->rs_strategy = bstrategy;
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/* scan the relation */
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while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL) {
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CHECK_FOR_INTERRUPTS();
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/* must hold a buffer lock to call HeapTupleSatisfiesVisibility */
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
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if (HeapTupleSatisfiesVisibility(tuple, SnapshotNow, scan->rs_cbuf)) {
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stat.tuple_len += tuple->t_len;
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stat.tuple_count++;
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} else {
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stat.dead_tuple_len += tuple->t_len;
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stat.dead_tuple_count++;
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}
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LockBuffer(scan->rs_cbuf, BUFFER_LOCK_UNLOCK);
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/*
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* To avoid physically reading the table twice, try to do the
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* free-space scan in parallel with the heap scan. However,
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* heap_getnext may find no tuples on a given page, so we cannot
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* simply examine the pages returned by the heap scan.
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*/
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tupblock = BlockIdGetBlockNumber(&tuple->t_self.ip_blkid);
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while (block <= tupblock) {
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CHECK_FOR_INTERRUPTS();
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buffer = ReadBufferExtended(rel, MAIN_FORKNUM, block, RBM_NORMAL, bstrategy);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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stat.free_space += PageGetHeapFreeSpace((Page)BufferGetPage(buffer));
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UnlockReleaseBuffer(buffer);
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block++;
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}
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}
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heap_endscan(scan);
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while (block < nblocks) {
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CHECK_FOR_INTERRUPTS();
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buffer = ReadBufferExtended(rel, MAIN_FORKNUM, block, RBM_NORMAL, bstrategy);
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LockBuffer(buffer, BUFFER_LOCK_SHARE);
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stat.free_space += PageGetHeapFreeSpace((Page)BufferGetPage(buffer));
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UnlockReleaseBuffer(buffer);
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block++;
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}
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relation_close(rel, AccessShareLock);
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stat.table_len = (uint64)nblocks * BLCKSZ;
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return build_pgstattuple_type(&stat, fcinfo);
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}
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/*
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* pgstat_btree_page -- check tuples in a btree page
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*/
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static void pgstat_btree_page(pgstattuple_type* stat, Relation rel, BlockNumber blkno, BufferAccessStrategy bstrategy)
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{
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Buffer buf;
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Page page;
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buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
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LockBuffer(buf, BT_READ);
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page = BufferGetPage(buf);
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/* Page is valid, see what to do with it */
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if (PageIsNew(page)) {
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/* fully empty page */
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stat->free_space += BLCKSZ;
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} else {
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BTPageOpaqueInternal opaque;
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OffsetNumber maxoff;
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opaque = (BTPageOpaqueInternal)PageGetSpecialPointer(page);
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if (opaque->btpo_flags & (BTP_DELETED | BTP_HALF_DEAD)) {
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/* recyclable page */
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stat->free_space += BLCKSZ;
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} else if (P_ISLEAF(opaque)) {
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maxoff = PageGetMaxOffsetNumber(page);
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pgstat_index_page(stat, page, P_FIRSTDATAKEY(opaque), maxoff);
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} else {
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/* root or node */
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}
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}
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_bt_relbuf(rel, buf);
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}
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/*
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* pgstat_hash_page -- check tuples in a hash page
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*/
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static void pgstat_hash_page(pgstattuple_type* stat, Relation rel, BlockNumber blkno, BufferAccessStrategy bstrategy)
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{
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Buffer buf;
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Page page;
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OffsetNumber maxoff;
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_hash_getlock(rel, blkno, HASH_SHARE);
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buf = _hash_getbuf_with_strategy(rel, blkno, HASH_READ, 0, bstrategy);
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page = BufferGetPage(buf);
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if (PageGetSpecialSize(page) == MAXALIGN(sizeof(HashPageOpaqueData))) {
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HashPageOpaque opaque;
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opaque = (HashPageOpaque)PageGetSpecialPointer(page);
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switch (opaque->hasho_flag) {
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case LH_UNUSED_PAGE:
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stat->free_space += BLCKSZ;
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break;
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case LH_BUCKET_PAGE:
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case LH_OVERFLOW_PAGE:
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maxoff = PageGetMaxOffsetNumber(page);
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pgstat_index_page(stat, page, FirstOffsetNumber, maxoff);
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break;
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case LH_BITMAP_PAGE:
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case LH_META_PAGE:
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default:
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break;
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}
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} else {
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/* maybe corrupted */
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}
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_hash_relbuf(rel, buf);
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_hash_droplock(rel, blkno, HASH_SHARE);
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}
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/*
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* pgstat_gist_page -- check tuples in a gist page
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*/
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static void pgstat_gist_page(pgstattuple_type* stat, Relation rel, BlockNumber blkno, BufferAccessStrategy bstrategy)
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{
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Buffer buf;
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Page page;
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OffsetNumber maxoff;
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buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
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LockBuffer(buf, GIST_SHARE);
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gistcheckpage(rel, buf);
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page = BufferGetPage(buf);
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if (GistPageIsLeaf(page)) {
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maxoff = PageGetMaxOffsetNumber(page);
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pgstat_index_page(stat, page, FirstOffsetNumber, maxoff);
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} else {
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/* root or node */
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}
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UnlockReleaseBuffer(buf);
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}
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/*
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* pgstat_index -- returns live/dead tuples info in a generic index
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*/
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static Datum pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn, FunctionCallInfo fcinfo)
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{
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BlockNumber nblocks;
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BlockNumber blkno;
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BufferAccessStrategy bstrategy;
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pgstattuple_type stat = {0};
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/* prepare access strategy for this index */
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bstrategy = GetAccessStrategy(BAS_BULKREAD);
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blkno = start;
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for (;;) {
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/* Get the current relation length */
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LockRelationForExtension(rel, ExclusiveLock);
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nblocks = RelationGetNumberOfBlocks(rel);
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UnlockRelationForExtension(rel, ExclusiveLock);
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/* Quit if we've scanned the whole relation */
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if (blkno >= nblocks) {
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stat.table_len = (uint64)nblocks * BLCKSZ;
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break;
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}
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for (; blkno < nblocks; blkno++) {
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CHECK_FOR_INTERRUPTS();
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pagefn(&stat, rel, blkno, bstrategy);
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}
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}
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relation_close(rel, AccessShareLock);
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return build_pgstattuple_type(&stat, fcinfo);
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}
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/*
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* pgstat_index_page -- for generic index page
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*/
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static void pgstat_index_page(pgstattuple_type* stat, Page page, OffsetNumber minoff, OffsetNumber maxoff)
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{
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OffsetNumber i;
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stat->free_space += PageGetFreeSpace(page);
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for (i = minoff; i <= maxoff; i = OffsetNumberNext(i)) {
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ItemId itemid = PageGetItemId(page, i);
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if (ItemIdIsDead(itemid)) {
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stat->dead_tuple_count++;
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stat->dead_tuple_len += ItemIdGetLength(itemid);
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} else {
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stat->tuple_count++;
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stat->tuple_len += ItemIdGetLength(itemid);
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}
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}
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}
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