Feat(bigquery): transpile format_datetime, datetime_trunc to duckdb

[skadel]

No description provided.

[georgesittas]

Hi @skadel, thanks for the PR! Please run make style to format & lint the code, I'll review shortly.

[georgesittas]

Seems good based on https://github.com/tobymao/sqlglot/pull/3894/files#r1712999820, but I may try a few cases myself in BQ to double check this later or tomorrow.

[georgesittas]

@skadel I tried a few examples and found at least one category that fails with the FORMAT_DATETIME -> FORMAT_DATE change. Check this out:

-- Works
SELECT FORMAT_DATETIME('%x', '2008-12-25 12:05:01') AS US_format

-- Doesn't work:  Could not cast literal "2008-12-25 12:05:01" to type DATE at [1:26]
-- This is the query we get when we read/write with BQ using this PR
SELECT FORMAT_DATE('%x', '2008-12-25 12:05:01') AS US_format

Let's not convert any of these two functions into the other one, these transformations are tricky to get right and I don't want to risk breaking users' queries with this.

Perhaps you could leverage the fact that at parse time you produce exp.TsOrDsToTimestamp(this=seq_get(args, 1)) for the FORMAT_DATETIME one, and so in the timetostr_sql method you could check this and generate the same function name instead of FORMAT_DATE.

[skadel]

@skadel I tried a few examples and found at least one category that fails with the FORMAT_DATETIME -> FORMAT_DATE change. Check this out:

-- Works
SELECT FORMAT_DATETIME('%x', '2008-12-25 12:05:01') AS US_format

-- Doesn't work:  Could not cast literal "2008-12-25 12:05:01" to type DATE at [1:26]
-- This is the query we get when we read/write with BQ using this PR
SELECT FORMAT_DATE('%x', '2008-12-25 12:05:01') AS US_format

Let's not convert any of these two functions into the other one, these transformations are tricky to get right and I don't want to risk breaking users' queries with this.

Perhaps you could leverage the fact that at parse time you produce exp.TsOrDsToTimestamp(this=seq_get(args, 1)) for the FORMAT_DATETIME one, and so in the timetostr_sql method you could check this and generate the same function name instead of FORMAT_DATE.

You're right, i thought that TsOrDsToTimestamp cast it to timestamp so i tested SELECT FORMAT_DATE('%x', CAST('2008-12-25 12:05:01' AS DATETIME)). But you're right, it's better to keep the same function.

[georgesittas]

Thank you for the contribution 🙌