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a.pervushinadanolivo
a.pervushina
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danolivo
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Add tests for the 'Learn after an query interruption by timeout' feature. Fix the bug with false finished node. Add some DEBUG messages. Just for conveniency.
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6 files changed

+182
-6
lines changed

‎Makefile‎

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Original file line numberDiff line numberDiff line change
@@ -23,6 +23,7 @@ REGRESS = aqo_disabled \
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unsupported \
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clean_aqo_data \
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plancache \
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statement_timeout \
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top_queries
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fdw_srcdir = $(top_srcdir)/contrib/postgres_fdw

‎expected/statement_timeout.out‎

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@@ -0,0 +1,109 @@
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-- Check the learning-on-timeout feature
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-- For stabilized reproduction autovacuum must be disabled.
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CREATE FUNCTION check_estimated_rows(text) RETURNS TABLE (estimated int)
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LANGUAGE plpgsql AS $$
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DECLARE
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ln text;
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tmp text[];
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first_row bool := true;
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BEGIN
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FOR ln IN
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execute format('explain %s', $1)
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LOOP
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IF first_row THEN
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first_row := false;
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tmp := regexp_match(ln, 'rows=(\d*)');
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RETURN QUERY SELECT tmp[1]::int;
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END IF;
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END LOOP;
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END; $$;
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CREATE TABLE t AS SELECT * FROM generate_series(1,100) AS x;
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ANALYZE t;
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DELETE FROM t WHERE x > 5; -- Force optimizer to make overestimated prediction.
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CREATE EXTENSION IF NOT EXISTS aqo;
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SET aqo.mode = 'learn';
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SET aqo.show_details = 'off';
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SET aqo.learn_statement_timeout = 'on';
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SET statement_timeout = 800; -- [0.8s]
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SELECT *, pg_sleep(1) FROM t;
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NOTICE: [AQO] Time limit for execution of the statement was expired. AQO tried to learn on partial data.
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ERROR: canceling statement due to statement timeout
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;'); -- haven't any partial data
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check_estimated_rows
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----------------------
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100
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(1 row)
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-- Don't learn because running node has smaller cardinality than an optimizer prediction
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SET statement_timeout = 3500;
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SELECT *, pg_sleep(1) FROM t;
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NOTICE: [AQO] Time limit for execution of the statement was expired. AQO tried to learn on partial data.
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ERROR: canceling statement due to statement timeout
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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check_estimated_rows
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----------------------
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100
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(1 row)
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-- We have a real learning data.
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SET statement_timeout = 10000;
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SELECT *, pg_sleep(1) FROM t;
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x | pg_sleep
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---+----------
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1 |
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2 |
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3 |
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4 |
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5 |
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(5 rows)
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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check_estimated_rows
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----------------------
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5
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(1 row)
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-- Force to make an underestimated prediction
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DELETE FROM t WHERE x > 2;
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ANALYZE t;
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INSERT INTO t (x) (SELECT * FROM generate_series(3,5) AS x);
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TRUNCATE aqo_data;
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SET statement_timeout = 800;
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SELECT *, pg_sleep(1) FROM t; -- Not learned
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NOTICE: [AQO] Time limit for execution of the statement was expired. AQO tried to learn on partial data.
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ERROR: canceling statement due to statement timeout
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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check_estimated_rows
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----------------------
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2
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(1 row)
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SET statement_timeout = 3500;
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SELECT *, pg_sleep(1) FROM t; -- Learn!
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NOTICE: [AQO] Time limit for execution of the statement was expired. AQO tried to learn on partial data.
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ERROR: canceling statement due to statement timeout
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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check_estimated_rows
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----------------------
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3
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(1 row)
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SET statement_timeout = 5500;
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SELECT *, pg_sleep(1) FROM t; -- Get reliable data
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x | pg_sleep
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---+----------
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1 |
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2 |
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3 |
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4 |
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5 |
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(5 rows)
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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check_estimated_rows
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----------------------
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5
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(1 row)
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DROP TABLE t;
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DROP EXTENSION aqo;

‎learn_cache.c‎

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Original file line numberDiff line numberDiff line change
@@ -86,6 +86,7 @@ lc_update_fss(uint64 fs, int fss, OkNNrdata *data, List *relids)
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* Collision found: the same {fs,fss}, but something different.
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* For simplicity - just don't update.
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*/
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elog(DEBUG5, "[AQO]: A collision found in the temporary storage.");
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LWLockRelease(&aqo_state->lock);
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return false;
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}
@@ -134,6 +135,8 @@ lc_update_fss(uint64 fs, int fss, OkNNrdata *data, List *relids)
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/* Check the invariant */
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Assert((uint32)(ptr - (char *) hdr) == size);
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elog(DEBUG5, "DSM entry: %s, targets: %d.",
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found ? "Reused" : "New entry", hdr->rows);
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LWLockRelease(&aqo_state->lock);
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return true;
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}

‎machine_learning.c‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -199,8 +199,7 @@ OkNNr_learn(OkNNrdata *data, double *features, double target, double rfactor)
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return data->rows;
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}
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if (data->rows < aqo_K)
202+
else if (data->rows < aqo_K)
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{
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/* We don't reach a limit of stored neighbors */
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@@ -275,6 +274,5 @@ OkNNr_learn(OkNNrdata *data, double *features, double target, double rfactor)
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}
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}
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}
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return data->rows;
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}

‎postprocessing.c‎

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Original file line numberDiff line numberDiff line change
@@ -349,11 +349,12 @@ should_learn(PlanState *ps, AQOPlanNode *node, aqo_obj_stat *ctx,
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}
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/* Has the executor finished its work? */
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if (TupIsNull(ps->ps_ResultTupleSlot) &&
352+
if (!ps->instrument->running && TupIsNull(ps->ps_ResultTupleSlot) &&
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ps->instrument->nloops > 0.) /* Node was visited by executor at least once. */
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{
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/* This is much more reliable data. So we can correct our prediction. */
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if (ctx->learn && aqo_show_details && fabs(*nrows - predicted) / predicted > 0.2)
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if (ctx->learn && aqo_show_details &&
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fabs(*nrows - predicted) / predicted > 0.2)
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elog(NOTICE,
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"[AQO] Learn on a finished plan node (%lu, %d), "
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"predicted rows: %.0lf, updated prediction: %.0lf",
@@ -693,7 +694,7 @@ aqo_timeout_handler(void)
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ctx.learn = query_context.learn_aqo;
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ctx.isTimedOut = true;
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elog(NOTICE, "[AQO] Time limit for execution of the statement was expired. Try to learn on partial data.");
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elog(NOTICE, "[AQO] Time limit for execution of the statement was expired. AQO tried to learn on partial data.");
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learnOnPlanState(timeoutCtl.queryDesc->planstate, (void *) &ctx);
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}
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‎sql/statement_timeout.sql‎

Lines changed: 64 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,64 @@
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-- Check the learning-on-timeout feature
2+
-- For stabilized reproduction autovacuum must be disabled.
3+
4+
CREATE FUNCTION check_estimated_rows(text) RETURNS TABLE (estimated int)
5+
LANGUAGE plpgsql AS $$
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DECLARE
7+
ln text;
8+
tmp text[];
9+
first_row bool := true;
10+
BEGIN
11+
FOR ln IN
12+
execute format('explain %s', $1)
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LOOP
14+
IF first_row THEN
15+
first_row := false;
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tmp := regexp_match(ln, 'rows=(\d*)');
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RETURN QUERY SELECT tmp[1]::int;
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END IF;
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END LOOP;
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END; $$;
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CREATE TABLE t AS SELECT * FROM generate_series(1,100) AS x;
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ANALYZE t;
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DELETE FROM t WHERE x > 5; -- Force optimizer to make overestimated prediction.
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CREATE EXTENSION IF NOT EXISTS aqo;
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SET aqo.mode = 'learn';
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SET aqo.show_details = 'off';
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SET aqo.learn_statement_timeout = 'on';
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31+
SET statement_timeout = 800; -- [0.8s]
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SELECT *, pg_sleep(1) FROM t;
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;'); -- haven't any partial data
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35+
-- Don't learn because running node has smaller cardinality than an optimizer prediction
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SET statement_timeout = 3500;
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SELECT *, pg_sleep(1) FROM t;
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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40+
-- We have a real learning data.
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SET statement_timeout = 10000;
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SELECT *, pg_sleep(1) FROM t;
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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45+
-- Force to make an underestimated prediction
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DELETE FROM t WHERE x > 2;
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ANALYZE t;
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INSERT INTO t (x) (SELECT * FROM generate_series(3,5) AS x);
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TRUNCATE aqo_data;
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51+
SET statement_timeout = 800;
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SELECT *, pg_sleep(1) FROM t; -- Not learned
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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SET statement_timeout = 3500;
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SELECT *, pg_sleep(1) FROM t; -- Learn!
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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SET statement_timeout = 5500;
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SELECT *, pg_sleep(1) FROM t; -- Get reliable data
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SELECT check_estimated_rows('SELECT *, pg_sleep(1) FROM t;');
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DROP TABLE t;
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DROP EXTENSION aqo;

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