feat(annotate_types): propagate type through Lag/Lead/NthValue window functions [CLAUDE]#7652
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… functions Registers Lag, Lead, and NthValue in the base EXPRESSION_METADATA with an _annotate_by_args(e, "this") annotator so that the return type follows the type of the first argument. Previously these resolved to UNKNOWN. Note: the 3-arg LAG/LEAD(col, offset, default) form could in principle widen the result type to the common type of col and default; that is deferred to a follow-up. Propagating "this" is strictly correct for the common cases (default omitted, or default is a NULL/compatible literal). [CLAUDE] Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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VaggelisD
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May 18, 2026
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Thank you for the PR once again @RichardHughes-amp! Leaving a few comments
| exp.HavingMax, | ||
| exp.Lag, | ||
| exp.LastValue, | ||
| exp.Lead, |
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Can we remove exp.Lead from bigquery's typing? it's also on "this" so its redundant
| exp.Filter, | ||
| exp.FirstValue, | ||
| exp.HavingMax, | ||
| exp.Lag, |
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BigQuery's exp.Lag typing is also based on default, could that true for more dialects?
| exp.LastValue, | ||
| exp.Lead, | ||
| exp.Limit, | ||
| exp.NthValue, |
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Similar to exp.Lead, we can remove the BQ entry
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What it says on the tin. Lag/Lead/NthValue can only propagate type from the column they're selecting from.