feat(duckdb): transpile BigQuery ARRAY_CONCAT_AGG to DuckDB#7891
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sirockin wants to merge 3 commits into
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feat(duckdb): transpile BigQuery ARRAY_CONCAT_AGG to DuckDB#7891sirockin wants to merge 3 commits into
sirockin wants to merge 3 commits into
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…IST(...)) BigQuery's `ARRAY_CONCAT_AGG(expr)` concatenates arrays into a single flat array. DuckDB has no direct equivalent, but `FLATTEN(LIST(expr))` achieves the same result: `LIST` collects the arrays into a nested list, then `FLATTEN` unnests one level. Adds: - `ARRAY_CONCAT_AGG` → `FLATTEN(LIST(...))` mapping in DuckDB generator - Transpilation test (BigQuery → DuckDB round-trip)
geooo109
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Jul 17, 2026
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ARRAY_CONCAT_AGG(
expression
[ ORDER BY key [ { ASC | DESC } ] [, ... ] ]
[ LIMIT n ]
)
From the docs ^ of bq, so let's also check what happens in the case of ORDER BY case and the LIMIT n.
- Replace FLATTEN(LIST(x)) with FLATTEN(ARRAY_AGG(x) FILTER(WHERE NOT x IS NULL)) so all-NULL inputs return NULL (matching BigQuery) - Use expression API via new arrayconcatagg_sql method instead of inline lambda with f-string - Fix test input to use valid BigQuery syntax (ARRAY_CONCAT_AGG requires an array argument, not a scalar) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
geooo109
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Jul 20, 2026
- Remove ArrayConcatAgg from TRANSFORMS dict (auto-discovered via
method name convention)
- Use self.func("FLATTEN", ...) instead of self.sql(exp.Flatten(...))
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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@sirockin is this still a draft? What's pending? |
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@georgesittas we should check the I think |
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Summary
BigQuery's
ARRAY_CONCAT_AGG(expr)concatenates arrays into a single flat array. DuckDB has no direct equivalent, butFLATTEN(LIST(expr))achieves the same result:LISTcollects the arrays into a nested list, thenFLATTENunnests one level.Changes
ARRAY_CONCAT_AGG→FLATTEN(LIST(...))mapping inDuckDB.GeneratorMotivation
We use sqlglot to transpile BigQuery SQL models to DuckDB for local testing via sqlmesh.
ARRAY_CONCAT_AGGis used in several of our production models but was not previously transpiled.