Blocked on https://github.com/hasura/graphql-engine-mono/pull/1640.
While fiddling with BigQuery I noticed a severe issue with offset/limit for array-aggregates. I've fixed it now.
The basic problem was that I was using a query like this:
```graphql
query MyQuery {
hasura_Artist(order_by: {artist_self_id: asc}) {
artist_self_id
albums_aggregate(order_by: {album_self_id: asc}, limit: 2) {
nodes {
album_self_id
}
aggregate {
count
}
}
}
}
```
Producing this SQL:
```sql
SELECT `t_Artist1`.`artist_self_id` AS `artist_self_id`,
STRUCT(IFNULL(`aa_albums1`.`nodes`, NULL) AS `nodes`, IFNULL(`aa_albums1`.`aggregate`, STRUCT(0 AS `count`)) AS `aggregate`) AS `albums_aggregate`
FROM `hasura`.`Artist` AS `t_Artist1`
LEFT OUTER JOIN (SELECT ARRAY_AGG(STRUCT(`t_Album1`.`album_self_id` AS `album_self_id`) ORDER BY (`t_Album1`.`album_self_id`) ASC) AS `nodes`,
STRUCT(COUNT(*) AS `count`) AS `aggregate`,
`t_Album1`.`artist_other_id` AS `artist_other_id`
FROM (SELECT *
FROM `hasura`.`Album` AS `t_Album1`
ORDER BY (`t_Album1`.`album_self_id`) ASC NULLS FIRST
-- PROBLEM HERE
LIMIT @param0) AS `t_Album1`
GROUP BY `t_Album1`.`artist_other_id`)
AS `aa_albums1`
ON (`aa_albums1`.`artist_other_id` = `t_Artist1`.`artist_self_id`)
ORDER BY (`t_Artist1`.`artist_self_id`) ASC NULLS FIRST
```
Note the `LIMIT @param0` -- that is incorrect because we want to limit
per artist. Instead, we want:
```sql
SELECT `t_Artist1`.`artist_self_id` AS `artist_self_id`,
STRUCT(IFNULL(`aa_albums1`.`nodes`, NULL) AS `nodes`, IFNULL(`aa_albums1`.`aggregate`, STRUCT(0 AS `count`)) AS `aggregate`) AS `albums_aggregate`
FROM `hasura`.`Artist` AS `t_Artist1`
LEFT OUTER JOIN (SELECT ARRAY_AGG(STRUCT(`t_Album1`.`album_self_id` AS `album_self_id`) ORDER BY (`t_Album1`.`album_self_id`) ASC) AS `nodes`,
STRUCT(COUNT(*) AS `count`) AS `aggregate`,
`t_Album1`.`artist_other_id` AS `artist_other_id`
FROM (SELECT *,
-- ADDED
ROW_NUMBER() OVER(PARTITION BY artist_other_id) artist_album_index
FROM `hasura`.`Album` AS `t_Album1`
ORDER BY (`t_Album1`.`album_self_id`) ASC NULLS FIRST
) AS `t_Album1`
-- CHANGED
WHERE artist_album_index <= @param
GROUP BY `t_Album1`.`artist_other_id`)
AS `aa_albums1`
ON (`aa_albums1`.`artist_other_id` = `t_Artist1`.`artist_self_id`)
ORDER BY (`t_Artist1`.`artist_self_id`) ASC NULLS FIRST
```
That serves both the LIMIT/OFFSET function in the where clause. Then,
both the ARRAY_AGG and the COUNT are correct per artist.
I've updated my Haskell test suite to add regression tests for this. I'll push a commit for Python tests shortly. The tests still pass there.
This just fixes a case that we hadn't noticed.
https://github.com/hasura/graphql-engine-mono/pull/1641
GitOrigin-RevId: 49933fa5e09a9306c89565743ecccf2cb54eaa80
