feat(parser): parse IGNORE NULLS in (window) function calls

[stdrc]

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What's changed and what's your intention?

This is the first step towards #17601.

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[stdrc]

• feat(parser): parse IGNORE NULLS in (window) function calls #18028 👈
• refactor(parser): introduce ast::FunctionArgList to contain all info in () of function call #18029
• fix(meta): fix query rename visitor for complex func calls #18023
• main

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[st1page]

LGTM
(Surprised to find that NULLs is already a keyword

[xiangjinwu]

https://www.postgresql.org/docs/17/sql-expressions.html#SYNTAX-WINDOW-FUNCTIONS
Syntactically the following is possible:

function_name (...) FILTER ( WHERE ... IS NOT NULL ) OVER ( ... )

If FILTER is specified, then only the input rows for which the filter_clause evaluates to true are fed to the window function; other rows are discarded.

However,

Only window functions that are aggregates accept a FILTER clause.

ERROR:  FILTER is not implemented for non-aggregate window functions

[stdrc]

However,

Only window functions that are aggregates accept a FILTER clause.

ERROR:  FILTER is not implemented for non-aggregate window functions

Is this the PG behavior?

[xiangjinwu]

Yes everything in my comment above is about PostgreSQL.