mirror of https://github.com/citusdata/citus.git
164 lines
6.8 KiB
Plaintext
164 lines
6.8 KiB
Plaintext
--
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-- MULTI_AGG_APPROXIMATE_DISTINCT
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--
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-- Create HLL extension if present, print false result otherwise
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SELECT CASE WHEN COUNT(*) > 0 THEN
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'CREATE EXTENSION HLL'
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ELSE 'SELECT false AS hll_present' END
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AS create_cmd FROM pg_available_extensions()
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WHERE name = 'hll'
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\gset
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:create_cmd;
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hll_present
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---------------------------------------------------------------------
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f
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(1 row)
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SELECT public.explain_has_distributed_subplan($$
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EXPLAIN SELECT symbol_id,
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HLL_ADD_AGG(HLL_HASH_BIGINT(event_id)) AS event_hll_hash,
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HLL_CARDINALITY(HLL_ADD_AGG(HLL_HASH_BIGINT(event_id))) AS event_n_users
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FROM (
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SELECT event_time, composite_id, event_id, 4640476 symbol_id FROM "events"
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UNION ALL
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SELECT event_time, composite_id, event_id, 4640477 symbol_id FROM "events"
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) pushdown_events
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GROUP BY symbol_id;
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$$);
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ERROR: function hll_hash_bigint(bigint) does not exist
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HINT: No function matches the given name and argument types. You might need to add explicit type casts.
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QUERY:
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EXPLAIN SELECT symbol_id,
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HLL_ADD_AGG(HLL_HASH_BIGINT(event_id)) AS event_hll_hash,
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HLL_CARDINALITY(HLL_ADD_AGG(HLL_HASH_BIGINT(event_id))) AS event_n_users
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FROM (
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SELECT event_time, composite_id, event_id, 4640476 symbol_id FROM "events"
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UNION ALL
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SELECT event_time, composite_id, event_id, 4640477 symbol_id FROM "events"
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) pushdown_events
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GROUP BY symbol_id;
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CONTEXT: PL/pgSQL function explain_has_distributed_subplan(text) line XX at FOR over EXECUTE statement
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SET citus.coordinator_aggregation_strategy TO 'disabled';
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-- Try to execute count(distinct) when approximate distincts aren't enabled
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SELECT count(distinct l_orderkey) FROM lineitem;
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count
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---------------------------------------------------------------------
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2985
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(1 row)
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-- Check approximate count(distinct) at different precisions / error rates
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SET citus.count_distinct_error_rate = 0.1;
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SELECT count(distinct l_orderkey) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SET citus.count_distinct_error_rate = 0.01;
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SELECT count(distinct l_orderkey) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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-- Check approximate count(distinct) for different data types
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SELECT count(distinct l_partkey) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(distinct l_extendedprice) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(distinct l_shipdate) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(distinct l_comment) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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-- Check that we can execute approximate count(distinct) on complex expressions
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SELECT count(distinct (l_orderkey * 2 + 1)) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(distinct extract(month from l_shipdate)) AS my_month FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(distinct l_partkey) / count(distinct l_orderkey) FROM lineitem;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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-- Check that we can execute approximate count(distinct) on select queries that
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-- contain different filter, join, sort and limit clauses
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SELECT count(distinct l_orderkey) FROM lineitem
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WHERE octet_length(l_comment) + octet_length('randomtext'::text) > 40;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(DISTINCT l_orderkey) FROM lineitem, orders
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WHERE l_orderkey = o_orderkey AND l_quantity < 5;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT count(DISTINCT l_orderkey) as distinct_order_count, l_quantity FROM lineitem
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WHERE l_quantity < 32.0
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GROUP BY l_quantity
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ORDER BY distinct_order_count ASC, l_quantity ASC
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LIMIT 10;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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-- Check that approximate count(distinct) works at a table in a schema other than public
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-- create necessary objects
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SET citus.next_shard_id TO 20000000;
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SET citus.next_placement_id TO 20000000;
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CREATE SCHEMA test_count_distinct_schema;
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CREATE TABLE test_count_distinct_schema.nation_hash(
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n_nationkey integer not null,
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n_name char(25) not null,
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n_regionkey integer not null,
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n_comment varchar(152)
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);
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SELECT create_distributed_table('test_count_distinct_schema.nation_hash', 'n_nationkey', 'hash');
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create_distributed_table
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---------------------------------------------------------------------
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(1 row)
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\copy test_count_distinct_schema.nation_hash FROM STDIN with delimiter '|';
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SET search_path TO public;
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SET citus.count_distinct_error_rate TO 0.01;
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SELECT COUNT (DISTINCT n_regionkey) FROM test_count_distinct_schema.nation_hash;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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-- test with search_path is set
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SET search_path TO test_count_distinct_schema;
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SELECT COUNT (DISTINCT n_regionkey) FROM nation_hash;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SET search_path TO public;
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-- If we have an order by on count(distinct) that we intend to push down to
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-- worker nodes, we need to error out. Otherwise, we are fine.
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SET citus.limit_clause_row_fetch_count = 1000;
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SELECT l_returnflag, count(DISTINCT l_shipdate) as count_distinct, count(*) as total
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FROM lineitem
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GROUP BY l_returnflag
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ORDER BY count_distinct
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LIMIT 10;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT l_returnflag, count(DISTINCT l_shipdate) as count_distinct, count(*) as total
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FROM lineitem
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GROUP BY l_returnflag
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ORDER BY total
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LIMIT 10;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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SELECT
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l_partkey,
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count(l_partkey) FILTER (WHERE l_shipmode = 'AIR'),
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count(DISTINCT l_partkey) FILTER (WHERE l_shipmode = 'AIR'),
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count(DISTINCT CASE WHEN l_shipmode = 'AIR' THEN l_partkey ELSE NULL END)
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FROM lineitem
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GROUP BY l_partkey
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ORDER BY 2 DESC, 1 DESC
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LIMIT 10;
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ERROR: cannot compute count (distinct) approximation
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HINT: You need to have the hll extension loaded.
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-- Check that we can revert config and disable count(distinct) approximations
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SET citus.count_distinct_error_rate = 0.0;
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SELECT count(distinct l_orderkey) FROM lineitem;
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count
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---------------------------------------------------------------------
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2985
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(1 row)
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