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fix(replication): correct Postgres epoch constant (#4002) #4007

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fix(replication): correct Postgres epoch constant (#4002) #4007

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4 changes: 2 additions & 2 deletions internal-packages/replication/src/client.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -363,7 +363,7 @@ export class LogicalReplicationClient {
} else if (buffer[0] === 0x6b) {
// Primary keepalive message
const timestamp = Math.floor(
buffer.readUInt32BE(9) * 4294967.296 + buffer.readUInt32BE(13) / 1000 + 946080000000
buffer.readUInt32BE(9) * 4294967.296 + buffer.readUInt32BE(13) / 1000 + 946684800000
);
const shouldRespond = !!buffer.readInt8(17);
this.events.emit("heartbeat", { lsn, timestamp, shouldRespond });
Expand Down Expand Up @@ -658,7 +658,7 @@ export class LogicalReplicationClient {
const slice = lsn.split("/");
let [upperWAL, lowerWAL]: [number, number] = [parseInt(slice[0], 16), parseInt(slice[1], 16)];
// Timestamp as microseconds since midnight 2000-01-01
const now = Date.now() - 946080000000;
const now = Date.now() - 946684800000;
const upperTimestamp = Math.floor(now / 4294967.296);
const lowerTimestamp = Math.floor(now - upperTimestamp * 4294967.296);

@devin-ai-integration devin-ai-integration Bot Jun 20, 2026

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🟡 Lower 32 bits of ACK timestamp computed in milliseconds instead of microseconds

The lowerTimestamp on line 663 computes the remainder of the 64-bit timestamp split in milliseconds instead of microseconds. The comment on line 660 states the timestamp should be "microseconds since midnight 2000-01-01", and the upper 32 bits are correctly derived from microseconds via now / 4294967.296 (which equals now * 1000 / 2^32). However, lowerTimestamp = Math.floor(now - upperTimestamp * 4294967.296) yields a value that is the remainder in milliseconds — it's ~1000× too small. The correct formula is Math.floor(now * 1000 - upperTimestamp * 4294967296) or equivalently Math.floor((now - upperTimestamp * 4294967.296) * 1000). You can verify by comparing the parsing logic at internal-packages/replication/src/client.ts:366 which correctly performs the inverse: upper * 4294967.296 + lower / 1000 — note the /1000 on the lower part, confirming the lower 32 bits are expected to be in microseconds. This pre-existing bug means the standby status update timestamp sent to PostgreSQL (used for pg_stat_replication.reply_time monitoring) can be off by up to ~71.6 minutes.

Suggested change
const lowerTimestamp = Math.floor(now - upperTimestamp * 4294967.296);
const lowerTimestamp = Math.floor((now - upperTimestamp * 4294967.296) * 1000);
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if (lowerWAL === 4294967295) {
Expand Down