eloqkv2rdb: exported values silently corrupted — int32_t narrowing of numeric strings, TTL ms→s truncation, zset score precision loss #494

Summary

Three data-fidelity bugs in the offline RDB exporter (src/tools/eloqkv2rdb/eloqkv2rdb.cpp):

1. Numeric strings narrowed through int32_t (data corruption)

RedisRdbUtil::OutputString (~line 139):

if (std::regex_match(s, number_pattern))
{
    int32_t n = std::stol(s);   // <-- narrowing
    ...
    else if (n >= -2147483648 && n <= 2147483647)  // always true for int32_t

• Digit strings between 2^31 and 2^63 (10–19 digits, e.g. a user ID "9876543210") wrap on the long → int32_t conversion and are emitted as a different INT32-encoded value — silent corruption in the exported RDB.
• Digit strings ≥ 20 chars make std::stol throw std::out_of_range, uncaught in worker threads → crash.

Fix: parse into int64_t, fall through to raw-string encoding when the value exceeds the INT32 range (matching Redis rdbTryIntegerEncoding), and catch/route parse failures to the string path.

2. TTL truncated from milliseconds to seconds

OutputTTL (~line 230) emits a second-resolution EXPIRETIME (uint32_t expire = ttl / 1000). Redis RDB supports millisecond expiry (0xFC, 8-byte ms). Sub-second precision is lost on every exported key.

3. zset score precision loss

Line ~352 serializes scores with OutputString(std::to_string(score)) — std::to_string(double) formats with 6 fixed decimals, so scores that need full double precision (or large magnitudes) round-trip incorrectly. Use %.17g (or RDB binary score encoding) instead.

Impact

Exports used for migration produce silently wrong data: corrupted numeric values, shifted expiry, rounded scores.

Found during the module-docs review (#492); see docs/07-persistence-and-tools.md Gotchas.

🤖 Found with Claude Code