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What's changed and what's your intention?

Previously we reuse batch aggregator for first_value and last_value in OverWindow, and this required an O(n) iteration through the "current window" when evaluating output for each row. This PR introduces shortcut implementations fro these two special aggregate types to avoid the need of O(n) iteration.

This also benefits lag and lead because they are implemented with first_value and last_value under the hood.

A rough benchmark with a dumb query based on nexmark source showed a 392% source throughput increase introduced by this PR, during the first 10 minutes after streaming job creation.

Query:

CREATE VIEW all_points AS
SELECT
    account,
    key,
    SUM(delta) AS points
FROM (
    SELECT
        ((bidder * 2654435761) # (bidder >> 16)) % 10000 as account,
        auction % 3 as key,
        price % 10 as delta
    FROM bid
)
GROUP BY account, key;

-- rank = row_number + first_value

set rw_streaming_over_window_cache_policy = full;
CREATE MATERIALIZED VIEW rn AS
SELECT
    account,
    key,
    points,
    ROW_NUMBER() OVER (
        PARTITION BY key
        ORDER BY points DESC
    ) AS rn
FROM all_points;

set rw_streaming_over_window_cache_policy = recent;
CREATE SINK mv AS
SELECT
    account,
    key,
    points,
    FIRST_VALUE(rn) OVER (
        PARTITION BY key
        ORDER BY points DESC
        RANGE BETWEEN CURRENT ROW AND CURRENT ROW
    ) AS rank
FROM rn
WITH ( connector = 'blackhole', type = 'append-only', force_append_only = 'true');

Before:

After:

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added test labels as necessary. See details.
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).
• All checks passed in ./risedev check (or alias, ./risedev c)
• My PR changes performance-critical code. (Please run macro/micro-benchmarks and show the results.)

• My PR contains critical fixes that are necessary to be merged into the latest release. (Please check out the details)

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