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fix: mark record/aggregate encoders STABLE, not IMMUTABLE - #8
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to_toon, row_to_toon, and the toon_agg support functions are built on
to_json/row_to_json, which PostgreSQL itself marks STABLE because their
output depends on session GUCs (TimeZone, DateStyle, extra_float_digits).
The same timestamptz encodes differently across sessions:
SET TIME ZONE 'UTC';
SELECT row_to_toon(q) FROM (SELECT '2024-01-01 00:00+00'::timestamptz AS t) q;
-- t: "2024-01-01T00:00:00+00:00"
SET TIME ZONE 'America/New_York'; -- same input:
-- t: "2023-12-31T19:00:00-05:00"
Declaring them IMMUTABLE lets the planner constant-fold across GUC
changes and, worse, permits expression indexes that silently return
wrong results when read under a different TimeZone/DateStyle.
The pure string helpers (toon_escape, toon_quote_key, toon_quote_value,
toon_encode_field) are genuinely immutable and keep IMMUTABLE. A
regression test now pins the volatility of every function.
Fixes #2
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FEYjgkWDYiRMYwwRS985g5
# Conflicts: # AGENTS.md
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Resolve conflicts with #8 (volatility), #9 (delimiter validation) and #10 (NaN docs), which landed on master first: - toon_agg_sfunc: keep this branch's text[] state, mark it STABLE per #8, and run #9's delimiter guard before the NULL-record skip so an invalid delimiter raises even when the row is NULL. - Volatility test: replace toon_agg_sfunc_default with the functions this branch adds (rows_to_toon, toon_agg_rows_ffunc, toon_delim_ok, toon_rows_ok). - AGENTS.md: list the new aggregate helpers in place of the removed toon_agg_state / sfunc_default entries. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_014JAaWhjV4FjNThbcAAWksS
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toon_agg was O(n²) for two reasons: PostgreSQL flattens and re-expands SQL/plpgsql transition state on every call, and the finalizer built its output with a per-row concat loop. The default toon_agg(anycompatible) now collects rows with the C transition pg_catalog.array_append and encodes once at finalization via a new public rows_to_toon(anyarray, delim), a single set-based pass over json_array_elements(array_to_json(rows)). The 2-arg toon_agg(q, delim) keeps a plpgsql transition (text[] state) and stays quadratic; rows_to_toon(array_agg(q), delim) is the documented linear alternative. The toon_agg_state type is removed. NULL records are now skipped rather than NULL-poisoning the result, and [N] counts only encoded rows. Integrates the delimiter guard from #9 and STABLE volatility from #8 into the new transition function. Fixes #4.
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Fixes #2.
to_toon,row_to_toon, and thetoon_aggsupport functions wrapto_json/row_to_json, which PostgreSQL marks STABLE because their output depends onTimeZone,DateStyle, andextra_float_digits. Same input, different output across sessions — verified on PG 16.13. Declaring them IMMUTABLE permits expression indexes that silently return wrong results when read under different GUCs.The pure string helpers (
toon_escape,toon_quote_key,toon_quote_value,toon_encode_field) stay IMMUTABLE. A catalog-based regression test pins the volatility of every function (by explicit name list, so unrelated schema objects can't break it). AGENTS.md volatility guidance updated.Release note for users:
CREATE INDEX ... (to_toon(col))and similar expression indexes / generated columns will now fail with functions in index expression must be marked IMMUTABLE. That's intentional — such indexes were wrong-results hazards.Merge order: if #11 (perf) merges first, the volatility test's function list needs its new function names added — happy to rebase either way. Suite: 68/68.
🤖 Generated with Claude Code
https://claude.ai/code/session_01FEYjgkWDYiRMYwwRS985g5