fix(aggregates): refuse a floating aggregate that overflows a double

[abnegate]

Problem

Staging QA of the query-lib migration found that a floating aggregate past the range of a double returns a wrong number instead of an error. On MariaDB, a double column with two rows of 1e308 answers aggregate([sum]) and aggregate([avg]) with "0". One row correctly answers 1e308, and stddev raises error 1690, which the adapter already maps to Exception\Limit.

aggregate() is new in 8.x, so this blocks the release.

Root cause of the 0

The 0 comes from the engine, not from PDO or the adapter's casting. MariaDB and MySQL hold the overflowed sum as infinity (SUM(d) > 1e308 is true and SUM(d) = 0 is false on the same rows). The text protocol then writes an infinite DOUBLE as 0, because my_gcvt() prints 0 on DTOA_OVERFLOW. The client only ever receives the string "0". AVG is SUM / COUNT, so it overflows the same way.

Reproduced against mariadb:10.11 and mysql:8.0.43:

SELECT SUM(d), AVG(d) FROM f;   -- 0  0
SELECT SUM(d) + 0 FROM f;       -- ERROR 1690 (22003): DOUBLE value is out of range

The variance aggregates are worse on MariaDB. VAR_POP and VAR_SAMP go out as 0, and STDDEV turns an infinite variance into DBL_MAX and an undefined one into NULL. For {1e308, -1e308, 0}, STDDEV_POP answers NULL. MySQL raises 1690 for the variance aggregates but not for SUM or AVG.

The other engines differ. SQLite answers INF, which comes back as the float INF or the string "INF" depending on ATTR_STRINGIFY_FETCHES. PostgreSQL already raises 22003 value out of range: overflow, which maps to Limit.

sum() has the same problem on SQLite with stringified fetches. The engine sends INF, and the new sumOf() reads that as no number and returns 0. 7.4.2 handed the value back unchanged. MongoDB, Memory and Redis return INF from sum().

A second bug sits in the same path. sumOf() cast every value without a decimal point to an integer, so sum() answered PHP_INT_MAX for a single 1e308 row, which MariaDB writes as 1e308. It did the same to a DECIMAL sum past PHP_INT_MAX. 7.4.2 handed the string to the int|float return type, which kept the double, so this is a regression too.

Fix

• MariaDB and MySQL builders (Builder\RaisesFloatOverflow): SUM, AVG, VARIANCE, VAR_POP and VAR_SAMP compile as <aggregate> + 0, and STDDEV* compiles as SQRT(<variance> + 0). The addition runs the engine's own float range check (check_float_overflow), which raises error 1690 for a value that is not finite. processException already maps 1690 to Exception\Limit, the same as for stddev. An unaliased aggregate is aliased to the text the engine would have named it with, so its column name does not change.
• count() and sum() write their fast-path statement out by hand. That statement now takes its aggregate from the dialect builder, so it stays the statement the builder makes and sum() raises the same error.
• Database::aggregate() refuses a non-finite sum, average, deviation or variance with the same Limit error. This covers SQLite.
• sumOf() converts the engine's value the way PHP converts any numeric string: an integer when it is one and a double otherwise. It reads SQLite's INF, -INF and NAN as the doubles they name.
• Database::sum() refuses a non-finite sum from any adapter with the same Limit error, so sum() agrees with aggregate().

PostgreSQL needs no change. An aggregate now either answers the correct value or raises Exception\Limit, on every adapter that supports aggregations. Consumers map Limit to a 400.

Tests

Each new test fails without the fix:

• tests/unit/Builder/FloatOverflowTest.php: the SQL the MariaDB and MySQL builders compile for each aggregate, including unaliased ones, and that PostgreSQL's is unchanged.
• tests/unit/AggregateOverflowTest.php: a real SQLite database with both fetch modes. A sum or average past the range is refused, including inside one group, and a single 1e308 row still answers 1e308.
• tests/unit/Adapter/SumResultTest.php: sum() reads 1e308, -1.5e300 and a DECIMAL past PHP_INT_MAX as doubles.
• tests/unit/SumOverflowTest.php: sum() past the range is refused on SQLite (both fetch modes) and Memory, with and without filters and a bound, and a single 1e308 row still sums to 1e308.
• tests/e2e/Adapter/Scopes/DocumentTests.php::testSumOverflowIsRefused: the same through sum() on every adapter.
• tests/e2e/Adapter/Scopes/AggregationTests.php::testFloatAggregateOverflowIsRefused: sum, avg, a grouped sum, stddevPop and varSamp refused, and the largest finite sum and average still answered.

Three existing tests are updated for the new SQL. StatisticalAggregateContractTest accepts the population form SQRT(VAR_POP(...) + 0). EmptySetAggregateContractTest's fake engine now recognises ... + 0 AS. BuilderStatementTest's statement fixture now has SUM(...) + 0 for MariaDB and MySQL.

Verified locally:

• The new aggregate E2E fails on BASE for MariaDB, MySQL and SQLite. It passes on PostgreSQL, which was already correct. The new sum() E2E fails on BASE for every adapter but PostgreSQL. Both pass with the fix on MariaDB, MySQL, PostgreSQL, SQLite, MongoDB, Memory and Redis.
• 200 aggregation-related E2E tests (Count|Sum|Avg|Min|Max|GroupBy|Having|Stddev|Var|Aggregat|Bit|Distinct) pass on MariaDB 10.11, MySQL 8.0.43, PostgreSQL 16 and SQLite at this branch's head.
• Unit suite: the only failure, SwooleAbsentTest, comes from the local machine and fails on BASE too.
• composer lint and both composer check configurations are clean.

The full adapter E2E matrix runs in CI.

This needs a patch release, 8.2.2.

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📝 Walkthrough

Aggregate queries now pass through dialect builders. MySQL and MariaDB add overflow checks to floating aggregates, and returned aggregate values are checked for non-finite results. Sum result conversion and related tests are also updated.

Changes: Floating Aggregate Handling

Layer / File(s)	Summary
Compile aggregate queries through dialect builders src/Database/Adapter/SQL.php, tests/unit/Adapter/SumResultTest.php	count() and sum() now pass query objects to fetchAggregate(), which compiles them through the dialect builder. sumOf() converts numeric results through numeric addition.
Add floating overflow checks to MySQL and MariaDB src/Database/Builder/*, tests/unit/Builder/FloatOverflowTest.php, tests/unit/Adapter/Data/Builder/statements.json, tests/unit/EmptySetAggregateContractTest.php, tests/unit/StatisticalAggregateContractTest.php	MySQL and MariaDB compile floating aggregates with overflow checks. Standard-deviation aggregates use the square root of checked variance. Tests cover generated SQL and aggregate contracts.
Reject non-finite aggregate results src/Database/Trait/Documents.php, tests/unit/AggregateOverflowTest.php, tests/e2e/Adapter/Scopes/AggregationTests.php	aggregate() checks floating aggregate values and throws LimitException for out-of-range results. Unit and end-to-end tests cover overflowing and finite aggregate values.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant SQLAdapter
  participant MySQLBuilder
  participant Database
  participant Documents
  SQLAdapter->>MySQLBuilder: Compile aggregate query
  MySQLBuilder->>Database: Execute overflow-checked aggregate SQL
  Database-->>Documents: Return aggregate result row
  Documents->>Documents: Check floating aggregate values for finiteness

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Merge Risk: 🔵 Low · up to ce8eb

An overflowing direct sum can still return an incorrect value. Fix that path before merging, or explicitly accept the bounded edge-case risk.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 69.23% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 26 functions across 11 files. (1 skipped:…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

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Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: rejecting floating-point aggregate results that overflow a double.

Full details: Docstring Coverage

Explanation

Docstring coverage is 69.23% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 26 functions across 11 files. (1 skipped: 1 unsupported.)

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Actionable comments posted: 1

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Inline comments:
Review comments at @src/Database/Adapter/SQL.php:
- Line 2262: Update the direct SUM handling in sumOf() to reject non-finite
converted values by raising LimitException, including stringified infinity; do
not silently convert those results to 0.

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📥 Commits

Reviewing files that changed from the base of the PR and between d4b2787 and ce8eb0b.

📒 Files selected for processing: 12

• src/Database/Adapter/SQL.php
• src/Database/Builder/MariaDB.php
• src/Database/Builder/MySQL.php
• src/Database/Builder/RaisesFloatOverflow.php
• src/Database/Trait/Documents.php
• tests/e2e/Adapter/Scopes/AggregationTests.php
• tests/unit/Adapter/Data/Builder/statements.json
• tests/unit/Adapter/SumResultTest.php
• tests/unit/AggregateOverflowTest.php
• tests/unit/Builder/FloatOverflowTest.php
• tests/unit/EmptySetAggregateContractTest.php
• tests/unit/StatisticalAggregateContractTest.php

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