Home/ Questions/Q 6622067
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-25T21:21:26+00:00

Here is my table: CREATE TABLE `letters` ( `a` bigint(20) unsigned NOT NULL, `b`

  • 0

Here is my table:

CREATE TABLE `letters` (
  `a` bigint(20) unsigned NOT NULL,
  `b` bigint(20) unsigned NOT NULL,
  `c` bigint(20) unsigned NOT NULL,
  `d` bigint(20) unsigned NOT NULL,
  `e` bigint(20) unsigned NOT NULL,
  PRIMARY KEY (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8$$
  • The table will have about 1+ billion rows.
  • Each column can be queried; each column can be referenced. e.g.:
    • SELECT [any column] FROM letters WHERE [any / any other column] IN ([subquery or list]);

My question: what indices should I add to speed up any query in the format above? (Also, if possible, please try to describe ‘why’ it/they should be added so that I can learn from your answer).

Thanks!

— Extra info: inserts will happen on a fairly regular basis (a few/handful every second) but select queries will happen more frequently.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    Since any column can appear in the WHERE clause, you’ve to add an index for each of the column, except for the field a since is already the PRIMARY KEY and as such is already indexed.

    UPDATE: as for the subsequent discussion, Poodlehat pointed out that the column e has a low index selectivity, i.e. “The ratio of the number of distinct values in the indexed column / columns to the number of records in the table”. For this reason, it’s not clear whether adding an index on column e will help or slow down queries. So Lucas will try experimentally and hopefully share the results to us.

    • 0