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Jan
16
reviewed Reviewed Does MySQL have problems with nested insert like with subqueries in where?
Jan
16
comment Execution plan in simple query in PgSQL depends on offset clause, why?
As I see, changing work_mem clearly had its effect, nearly halving the execution time. However, it did not change the estimated costs and nor the plan, since this setting has no effect on the planner. If you had spinning disks, the difference would be much greater, I think. As per setting random_page_cost, it may depend on the type of your particular disk, see Greg Smith's answers here. Anyway, you can safely lower the value to 2, and with certain disks even to 1.
Jan
16
asked Performance of different precedence pseudocolumn solutions with LIMIT
Jan
16
answered Performance of different precedence pseudocolumn solutions with LIMIT
Jan
15
comment ERROR: could not find array type for datatype information_schema.sql_identifier
You don't need to make arrays for this. Just do ... WHERE column_name NOT IN (SELECT column_name ... )
Jan
15
comment ERROR: could not find array type for datatype information_schema.sql_identifier
And your question? What is your plan with those column names?
Jan
15
revised ERROR: could not find array type for datatype information_schema.sql_identifier
added 44 characters in body
Jan
15
reviewed No Action Needed What is the reason of Host 'host_name' is blocked in MySQL?
Jan
15
reviewed No Action Needed What is the reason of Host 'host_name' is blocked in MySQL?
Jan
15
revised Execution plan in simple query in PgSQL depends on offset clause, why?
added 26 characters in body
Jan
15
answered Execution plan in simple query in PgSQL depends on offset clause, why?
Jan
15
comment Finding similar values in columns
What RDBMS do you use? And I wouldn't call a name column id.
Jan
15
comment Improve sort performance in PostgreSQL?
When a sort does not fit into work_mem, it spills out to the disk. If happens, this is shown in the query plan. On the other hand, the sorting here took 876 kB of memory. It is very unlikely that this is bigger than the work_mem of any relatively recent PG instances.
Jan
15
comment tuning feed item's table query with multiple condition
Why is the mismatch between the plan and the text (133534 vs 400000 rows)?
Jan
15
revised tuning feed item's table query with multiple condition
added 37 characters in body
Jan
15
revised Help with normalization - Homework
edited tags
Jan
15
revised Payment methods conceptual and logical model
edited tags
Jan
15
comment tuning feed item's table query with multiple condition
Hpw do you measure those 4 seconds? Pushing so much data through a network connection can be slow. A query plan would help anyway.
Jan
15
revised tuning feed item's table query with multiple condition
deleted 15 characters in body
Jan
14
comment MAX function and group by usage - postgresql
If you don't use GROUP BY, you will get the aggregates for all the rows selected (as specified by the WHERE clause). In this case you can't specify other columns in the SELECT list. If you say GROUP BY id, aggregates will be computed for any values of id, in your case for single rows - that's useless.