mirror of https://github.com/postgres/postgres
Simon Riggs
10 years ago
parent
4d40494b11
commit
56e121a508
@ -0,0 +1,4 @@ |
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# Generated subdirectories |
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/log/ |
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/results/ |
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/tmp_check/ |
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@ -0,0 +1,21 @@ |
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# src/test/modules/tsm_system_time/Makefile
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MODULE_big = tsm_system_time
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OBJS = tsm_system_time.o $(WIN32RES)
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PGFILEDESC = "tsm_system_time - SYSTEM TABLESAMPLE method which accepts number rows of as a limit"
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EXTENSION = tsm_system_time
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DATA = tsm_system_time--1.0.sql
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REGRESS = tsm_system_time
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ifdef USE_PGXS |
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PG_CONFIG = pg_config
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PGXS := $(shell $(PG_CONFIG) --pgxs)
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include $(PGXS) |
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else |
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subdir = contrib/tsm_system_time
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top_builddir = ../..
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include $(top_builddir)/src/Makefile.global |
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include $(top_srcdir)/contrib/contrib-global.mk |
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endif |
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@ -0,0 +1,54 @@ |
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CREATE EXTENSION tsm_system_time; |
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CREATE TABLE test_tablesample (id int, name text) WITH (fillfactor=10); -- force smaller pages so we don't have to load too much data to get multiple pages |
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INSERT INTO test_tablesample SELECT i, repeat(i::text, 1000) FROM generate_series(0, 30) s(i) ORDER BY i; |
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ANALYZE test_tablesample; |
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_time (1000); |
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count |
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------- |
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31 |
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(1 row) |
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SELECT id FROM test_tablesample TABLESAMPLE system_time (1000) REPEATABLE (5432); |
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id |
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---- |
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7 |
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14 |
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21 |
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28 |
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4 |
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11 |
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18 |
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25 |
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1 |
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8 |
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15 |
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22 |
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29 |
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5 |
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12 |
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19 |
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26 |
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2 |
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9 |
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16 |
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23 |
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30 |
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6 |
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13 |
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20 |
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27 |
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3 |
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10 |
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17 |
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24 |
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0 |
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(31 rows) |
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EXPLAIN SELECT id FROM test_tablesample TABLESAMPLE system_time (100) REPEATABLE (10); |
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QUERY PLAN |
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------------------------------------------------------------------------------------ |
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Sample Scan (system_time) on test_tablesample (cost=0.00..100.25 rows=25 width=4) |
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(1 row) |
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-- done |
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DROP TABLE test_tablesample CASCADE; |
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@ -0,0 +1,14 @@ |
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CREATE EXTENSION tsm_system_time; |
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CREATE TABLE test_tablesample (id int, name text) WITH (fillfactor=10); -- force smaller pages so we don't have to load too much data to get multiple pages |
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INSERT INTO test_tablesample SELECT i, repeat(i::text, 1000) FROM generate_series(0, 30) s(i) ORDER BY i; |
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ANALYZE test_tablesample; |
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SELECT count(*) FROM test_tablesample TABLESAMPLE system_time (1000); |
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SELECT id FROM test_tablesample TABLESAMPLE system_time (1000) REPEATABLE (5432); |
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EXPLAIN SELECT id FROM test_tablesample TABLESAMPLE system_time (100) REPEATABLE (10); |
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-- done |
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DROP TABLE test_tablesample CASCADE; |
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@ -0,0 +1,40 @@ |
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/* src/test/modules/tablesample/tsm_system_time--1.0.sql */ |
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-- complain if script is sourced in psql, rather than via CREATE EXTENSION |
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\echo Use "CREATE EXTENSION tsm_system_time" to load this file. \quit |
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CREATE FUNCTION tsm_system_time_init(internal, int4, int4) |
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RETURNS void |
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AS 'MODULE_PATHNAME' |
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LANGUAGE C STRICT; |
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CREATE FUNCTION tsm_system_time_nextblock(internal) |
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RETURNS int4 |
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AS 'MODULE_PATHNAME' |
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LANGUAGE C STRICT; |
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CREATE FUNCTION tsm_system_time_nexttuple(internal, int4, int2) |
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RETURNS int2 |
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AS 'MODULE_PATHNAME' |
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LANGUAGE C STRICT; |
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CREATE FUNCTION tsm_system_time_end(internal) |
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RETURNS void |
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AS 'MODULE_PATHNAME' |
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LANGUAGE C STRICT; |
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CREATE FUNCTION tsm_system_time_reset(internal) |
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RETURNS void |
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AS 'MODULE_PATHNAME' |
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LANGUAGE C STRICT; |
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CREATE FUNCTION tsm_system_time_cost(internal, internal, internal, internal, internal, internal, internal) |
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RETURNS void |
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AS 'MODULE_PATHNAME' |
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LANGUAGE C STRICT; |
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INSERT INTO pg_tablesample_method VALUES('system_time', false, true, |
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'tsm_system_time_init', 'tsm_system_time_nextblock', |
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'tsm_system_time_nexttuple', '-', 'tsm_system_time_end', |
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'tsm_system_time_reset', 'tsm_system_time_cost'); |
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@ -0,0 +1,315 @@ |
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/*-------------------------------------------------------------------------
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* |
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* tsm_system_time.c |
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* interface routines for system_time tablesample method |
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* |
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* |
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* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group |
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* |
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* IDENTIFICATION |
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* contrib/tsm_system_time_rowlimit/tsm_system_time.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 "fmgr.h" |
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#include "access/tablesample.h" |
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#include "access/relscan.h" |
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#include "miscadmin.h" |
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#include "nodes/execnodes.h" |
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#include "nodes/relation.h" |
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#include "optimizer/clauses.h" |
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#include "storage/bufmgr.h" |
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#include "utils/sampling.h" |
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#include "utils/spccache.h" |
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#include "utils/timestamp.h" |
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PG_MODULE_MAGIC; |
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/*
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* State |
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*/ |
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typedef struct |
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{ |
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SamplerRandomState randstate; |
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uint32 seed; /* random seed */ |
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BlockNumber nblocks; /* number of block in relation */ |
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int32 time; /* time limit for sampling */ |
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TimestampTz start_time; /* start time of sampling */ |
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TimestampTz end_time; /* end time of sampling */ |
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OffsetNumber lt; /* last tuple returned from current block */ |
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BlockNumber step; /* step size */ |
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BlockNumber lb; /* last block visited */ |
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BlockNumber estblocks; /* estimated number of returned blocks (moving) */ |
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BlockNumber doneblocks; /* number of already returned blocks */ |
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} SystemSamplerData; |
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PG_FUNCTION_INFO_V1(tsm_system_time_init); |
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PG_FUNCTION_INFO_V1(tsm_system_time_nextblock); |
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PG_FUNCTION_INFO_V1(tsm_system_time_nexttuple); |
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PG_FUNCTION_INFO_V1(tsm_system_time_end); |
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PG_FUNCTION_INFO_V1(tsm_system_time_reset); |
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PG_FUNCTION_INFO_V1(tsm_system_time_cost); |
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static uint32 random_relative_prime(uint32 n, SamplerRandomState randstate); |
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/*
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* Initializes the state. |
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*/ |
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Datum |
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tsm_system_time_init(PG_FUNCTION_ARGS) |
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{ |
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TableSampleDesc *tsdesc = (TableSampleDesc *) PG_GETARG_POINTER(0); |
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uint32 seed = PG_GETARG_UINT32(1); |
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int32 time = PG_ARGISNULL(2) ? -1 : PG_GETARG_INT32(2); |
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HeapScanDesc scan = tsdesc->heapScan; |
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SystemSamplerData *sampler; |
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if (time < 1) |
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ereport(ERROR, |
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(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), |
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errmsg("invalid time limit"), |
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errhint("Time limit must be positive integer value."))); |
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sampler = palloc0(sizeof(SystemSamplerData)); |
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/* Remember initial values for reinit */ |
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sampler->seed = seed; |
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sampler->nblocks = scan->rs_nblocks; |
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sampler->lt = InvalidOffsetNumber; |
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sampler->estblocks = 2; |
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sampler->doneblocks = 0; |
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sampler->time = time; |
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sampler->start_time = GetCurrentTimestamp(); |
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sampler->end_time = TimestampTzPlusMilliseconds(sampler->start_time, |
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sampler->time); |
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sampler_random_init_state(sampler->seed, sampler->randstate); |
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/* Find relative prime as step size for linear probing. */ |
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sampler->step = random_relative_prime(sampler->nblocks, sampler->randstate); |
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/*
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* Randomize start position so that blocks close to step size don't have |
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* higher probability of being chosen on very short scan. |
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*/ |
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sampler->lb = sampler_random_fract(sampler->randstate) * (sampler->nblocks / sampler->step); |
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tsdesc->tsmdata = (void *) sampler; |
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PG_RETURN_VOID(); |
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} |
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/*
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* Get next block number or InvalidBlockNumber when we're done. |
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* |
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* Uses linear probing algorithm for picking next block. |
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*/ |
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Datum |
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tsm_system_time_nextblock(PG_FUNCTION_ARGS) |
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{ |
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TableSampleDesc *tsdesc = (TableSampleDesc *) PG_GETARG_POINTER(0); |
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SystemSamplerData *sampler = (SystemSamplerData *) tsdesc->tsmdata; |
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sampler->lb = (sampler->lb + sampler->step) % sampler->nblocks; |
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sampler->doneblocks++; |
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/* All blocks have been read, we're done */ |
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if (sampler->doneblocks > sampler->nblocks) |
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PG_RETURN_UINT32(InvalidBlockNumber); |
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/*
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* Update the estimations for time limit at least 10 times per estimated |
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* number of returned blocks to handle variations in block read speed. |
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*/ |
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if (sampler->doneblocks % Max(sampler->estblocks/10, 1) == 0) |
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{ |
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TimestampTz now = GetCurrentTimestamp(); |
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long secs; |
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int usecs; |
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int usecs_remaining; |
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int time_per_block; |
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TimestampDifference(sampler->start_time, now, &secs, &usecs); |
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usecs += (int) secs * 1000000; |
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time_per_block = usecs / sampler->doneblocks; |
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/* No time left, end. */ |
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TimestampDifference(now, sampler->end_time, &secs, &usecs); |
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if (secs <= 0 && usecs <= 0) |
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PG_RETURN_UINT32(InvalidBlockNumber); |
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/* Remaining microseconds */ |
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usecs_remaining = usecs + (int) secs * 1000000; |
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/* Recalculate estimated returned number of blocks */ |
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if (time_per_block < usecs_remaining && time_per_block > 0) |
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sampler->estblocks = sampler->time * time_per_block; |
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} |
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PG_RETURN_UINT32(sampler->lb); |
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} |
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/*
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* Get next tuple offset in current block or InvalidOffsetNumber if we are done |
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* with this block. |
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*/ |
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Datum |
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tsm_system_time_nexttuple(PG_FUNCTION_ARGS) |
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{ |
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TableSampleDesc *tsdesc = (TableSampleDesc *) PG_GETARG_POINTER(0); |
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OffsetNumber maxoffset = PG_GETARG_UINT16(2); |
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SystemSamplerData *sampler = (SystemSamplerData *) tsdesc->tsmdata; |
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OffsetNumber tupoffset = sampler->lt; |
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if (tupoffset == InvalidOffsetNumber) |
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tupoffset = FirstOffsetNumber; |
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else |
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tupoffset++; |
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if (tupoffset > maxoffset) |
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tupoffset = InvalidOffsetNumber; |
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sampler->lt = tupoffset; |
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PG_RETURN_UINT16(tupoffset); |
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} |
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/*
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* Cleanup method. |
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*/ |
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Datum |
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tsm_system_time_end(PG_FUNCTION_ARGS) |
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{ |
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TableSampleDesc *tsdesc = (TableSampleDesc *) PG_GETARG_POINTER(0); |
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pfree(tsdesc->tsmdata); |
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PG_RETURN_VOID(); |
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} |
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/*
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* Reset state (called by ReScan). |
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*/ |
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Datum |
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tsm_system_time_reset(PG_FUNCTION_ARGS) |
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{ |
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TableSampleDesc *tsdesc = (TableSampleDesc *) PG_GETARG_POINTER(0); |
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SystemSamplerData *sampler = (SystemSamplerData *) tsdesc->tsmdata; |
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sampler->lt = InvalidOffsetNumber; |
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sampler->start_time = GetCurrentTimestamp(); |
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sampler->end_time = TimestampTzPlusMilliseconds(sampler->start_time, |
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sampler->time); |
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sampler->estblocks = 2; |
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sampler->doneblocks = 0; |
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sampler_random_init_state(sampler->seed, sampler->randstate); |
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sampler->step = random_relative_prime(sampler->nblocks, sampler->randstate); |
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sampler->lb = sampler_random_fract(sampler->randstate) * (sampler->nblocks / sampler->step); |
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PG_RETURN_VOID(); |
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} |
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/*
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* Costing function. |
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*/ |
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Datum |
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tsm_system_time_cost(PG_FUNCTION_ARGS) |
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{ |
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PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
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Path *path = (Path *) PG_GETARG_POINTER(1); |
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RelOptInfo *baserel = (RelOptInfo *) PG_GETARG_POINTER(2); |
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List *args = (List *) PG_GETARG_POINTER(3); |
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BlockNumber *pages = (BlockNumber *) PG_GETARG_POINTER(4); |
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double *tuples = (double *) PG_GETARG_POINTER(5); |
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Node *limitnode; |
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int32 time; |
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BlockNumber relpages; |
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double reltuples; |
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double density; |
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double spc_random_page_cost; |
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limitnode = linitial(args); |
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limitnode = estimate_expression_value(root, limitnode); |
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if (IsA(limitnode, RelabelType)) |
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limitnode = (Node *) ((RelabelType *) limitnode)->arg; |
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if (IsA(limitnode, Const)) |
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time = DatumGetInt32(((Const *) limitnode)->constvalue); |
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else |
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{ |
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/* Default time (1s) if the estimation didn't return Const. */ |
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time = 1000; |
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} |
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relpages = baserel->pages; |
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reltuples = baserel->tuples; |
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/* estimate the tuple density */ |
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if (relpages > 0) |
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density = reltuples / (double) relpages; |
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else |
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density = (BLCKSZ - SizeOfPageHeaderData) / baserel->width; |
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/*
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* We equal random page cost value to number of ms it takes to read the |
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* random page here which is far from accurate but we don't have anything |
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* better to base our predicted page reads. |
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*/ |
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get_tablespace_page_costs(baserel->reltablespace, |
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&spc_random_page_cost, |
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NULL); |
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/*
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* Assumption here is that we'll never read less then 1% of table pages, |
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* this is here mainly because it is much less bad to overestimate than |
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* underestimate and using just spc_random_page_cost will probably lead |
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* to underestimations in general. |
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*/ |
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*pages = Min(baserel->pages, Max(time/spc_random_page_cost, baserel->pages/100)); |
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*tuples = rint(density * (double) *pages * path->rows / baserel->tuples); |
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path->rows = *tuples; |
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PG_RETURN_VOID(); |
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} |
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static uint32 |
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gcd (uint32 a, uint32 b) |
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{ |
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uint32 c; |
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while (a != 0) |
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{ |
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c = a; |
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a = b % a; |
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b = c; |
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} |
||||||
|
|
||||||
|
return b; |
||||||
|
} |
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|
|
||||||
|
static uint32 |
||||||
|
random_relative_prime(uint32 n, SamplerRandomState randstate) |
||||||
|
{ |
||||||
|
/* Pick random starting number, with some limits on what it can be. */ |
||||||
|
uint32 r = (uint32) sampler_random_fract(randstate) * n/2 + n/4, |
||||||
|
t; |
||||||
|
|
||||||
|
/*
|
||||||
|
* This should only take 2 or 3 iterations as the probability of 2 numbers |
||||||
|
* being relatively prime is ~61%. |
||||||
|
*/ |
||||||
|
while ((t = gcd(r, n)) > 1) |
||||||
|
{ |
||||||
|
CHECK_FOR_INTERRUPTS(); |
||||||
|
r /= t; |
||||||
|
} |
||||||
|
|
||||||
|
return r; |
||||||
|
} |
||||||
@ -0,0 +1,5 @@ |
|||||||
|
# tsm_system_time extension |
||||||
|
comment = 'SYSTEM TABLESAMPLE method which accepts time in milliseconds as a limit' |
||||||
|
default_version = '1.0' |
||||||
|
module_pathname = '$libdir/tsm_system_time' |
||||||
|
relocatable = true |
||||||
Loading…
Reference in new issue