getCount(). Perfs issues for multi columns primary key

Issue type:

[X ] question

Database system/driver: [X ] postgres

Version 0.2.18

I’m facing a perf issue when running getCount() Why when counting all records of a query, queryBuilder creates a SQL query that concatenates the columns that are part of the primary key ?

Typescript :

const query: SelectQueryBuilder<TEntity> = dbConnection
					.getRepository<TEntity>(entity)
					.createQueryBuilder(entity.name)
					.where(`"${entity.name}"."${id}"= :val`, {
						val: value.toLowerCase(),
					});

				const totalRecords: number = await query.getCount();

generated sql

SELECT COUNT(DISTINCT(
	CONCAT(
		"u"."a", 
		"u"."b",
		"u"."c")
	)
) as "cnt" FROM "sc"."tbl" "u"

That is destroying the performances for a table of 140K records. Creating an index on CONCAT using is not efficient, hard to maintain with 100 of tables, knowing that for some tables, some primay comumns are timestamp…

Is there a way or a parameter to set to avoid the concat and just running a kind of (select count(1) FROM "sc"."tbl" "u") ?

Rgds

[dsbert]

Note this also causes incorrect counts to be returned.

Here is an example.

You have two number columns set as primary keys - field1 and field2.

The following two rows will return the incorrect count.

{
	field1: 11,
	field2: 101
	// concat(field1, field2) = '11101'
},
{
	field1: 1,
	field2: 1101
	// concat(field1, field2) = '11101'
},

Count should be 2, but returns 1.

[imnotjames]

Can you confirm that #6870 fixes the issues you’re seeing?