query-planner

Why Mongo query for null filters in FETCH after performing IXSCAN

由 Deadly 提交于 2020-01-15 11:53:37
问题 According to Mongo Documentation, The { item : null } query matches documents that either contain the item field whose value is null or that do not contain the item field. I can't find documentation for this, but as far as I can tell, both cases (value is null or field is missing) are stored in the index as null . So if I do db.orders.createIndex({item: 1}) and then db.orders.find({item: null}) , I would expect an IXSCAN to find all documents that either contain the item field whose value is

Why Mongo query for null filters in FETCH after performing IXSCAN

由 南楼画角 提交于 2020-01-15 11:52:59
问题 According to Mongo Documentation, The { item : null } query matches documents that either contain the item field whose value is null or that do not contain the item field. I can't find documentation for this, but as far as I can tell, both cases (value is null or field is missing) are stored in the index as null . So if I do db.orders.createIndex({item: 1}) and then db.orders.find({item: null}) , I would expect an IXSCAN to find all documents that either contain the item field whose value is

why the query is executed 76 times slower when I put it into function?

由 不打扰是莪最后的温柔 提交于 2019-12-11 06:06:20
问题 When I put next query into function it goes 76times slower. The only difference at plan is: bitmap-index scan VS index scan Plan1: http://tatiyants.com/pev/#/plans/plan_1562919134481 Plan2: http://tatiyants.com/pev/#/plans/plan_1562918860704 plan1 EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT JSON) SELECT sum( t.group_suma ) OVER( PARTITION BY (t.o).id ) AS total_suma, * FROM ( SELECT sum( ocd.item_cost ) AS group_cost, sum( ocd.item_suma ) AS group_suma, max( (ocd.ic).consumed ) AS

Query plan caching with pl/pgsql

由 最后都变了- 提交于 2019-11-30 22:01:33
I am having troubles understanding how the query plan caching works for pl/pgsql. I want to built all-in-one queries with JOIN s and IF s, so I will have multiple and different query parameters, and I will be searching in more that one tables. At first I thought that using pl/pgsql will produce a different plan for each parameters combination, that is not the case, because I have more than one tables SQL commands that appear directly in a PL/pgSQL function must refer to the same tables and columns on every execution; that is, you cannot use a parameter as the name of a table or column in an

Query plan caching with pl/pgsql

由 大兔子大兔子 提交于 2019-11-30 17:26:46
问题 I am having troubles understanding how the query plan caching works for pl/pgsql. I want to built all-in-one queries with JOIN s and IF s, so I will have multiple and different query parameters, and I will be searching in more that one tables. At first I thought that using pl/pgsql will produce a different plan for each parameters combination, that is not the case, because I have more than one tables SQL commands that appear directly in a PL/pgSQL function must refer to the same tables and
订阅 query-planner