Function processMoveOutEvent

packages/electric-db-collection/src/electric.ts:1215–1252

(
    patterns: Array<MovePattern>,
    begin: () => void,
    write: (message: ChangeMessageOrDeleteKeyMessage<T>) => void,
    transactionStarted: boolean,
  )

   * Process move-out event: remove matching tags from rows and delete rows with empty tag sets
   */
  const processMoveOutEvent = (
    patterns: Array<MovePattern>,
    begin: () => void,
    write: (message: ChangeMessageOrDeleteKeyMessage<T>) => void,
    transactionStarted: boolean,
  ): boolean => {
    if (tagLength === undefined) {
      debug(
        `${collectionId ? `[${collectionId}] ` : ``}Received move-out message but no tag length set yet, ignoring`,
      )
      return transactionStarted
    }

    let txStarted = transactionStarted

    // Process all patterns and collect rows to delete
    for (const pattern of patterns) {
      // Find all rows that match this pattern
      const affectedRowIds = findRowsMatchingPattern(pattern, tagIndex)

      for (const rowId of affectedRowIds) {
        if (removeMatchingTagsFromRow(rowId, pattern)) {
          // Delete rows with empty tag sets
          if (!txStarted) {
            begin()
            txStarted = true
          }

          write({
            type: `delete`,
            key: rowId,
          })
        }
      }
    }

    return txStarted
  }

  /**
   * Process move-in event: re-activate conditions for rows matching the patterns.