MySQL :: MySQL 8.0 Reference Manual :: 29.12.11.1 The binary_log_transaction_compression_stats Table (original) (raw)

29.12.11.1 The binary_log_transaction_compression_stats Table

This table shows statistical information for transaction payloads written to the binary log and relay log, and can be used to calculate the effects of enabling binary log transaction compression. For information on binary log transaction compression, seeSection 7.4.4.5, “Binary Log Transaction Compression”.

Thebinary_log_transaction_compression_stats table is populated only when the server instance has a binary log, and the system variablebinlog_transaction_compression is set to ON. The statistics cover all transactions written to the binary log and relay log from the time the server was started or the table was truncated. Compressed transactions are grouped by the compression algorithm used, and uncompressed transactions are grouped together with the compression algorithm stated asNONE, so the compression ratio can be calculated.

Thebinary_log_transaction_compression_stats table has these columns:

• LOG_TYPE
  Whether these transactions were written to the binary log or relay log.
• COMPRESSION_TYPE
  The compression algorithm used to compress the transaction payloads. NONE means the payloads for these transactions were not compressed, which is correct in a number of situations (seeSection 7.4.4.5, “Binary Log Transaction Compression”).
• TRANSACTION_COUNTER
  The number of transactions written to this log type with this compression type.
• COMPRESSED_BYTES
  The total number of bytes that were compressed and then written to this log type with this compression type, counted after compression.
• UNCOMPRESSED_BYTES
  The total number of bytes before compression for this log type and this compression type.
• COMPRESSION_PERCENTAGE
  The compression ratio for this log type and this compression type, expressed as a percentage.
• FIRST_TRANSACTION_ID
  The ID of the first transaction that was written to this log type with this compression type.
• FIRST_TRANSACTION_COMPRESSED_BYTES
  The total number of bytes that were compressed and then written to the log for the first transaction, counted after compression.
• FIRST_TRANSACTION_UNCOMPRESSED_BYTES
  The total number of bytes before compression for the first transaction.
• FIRST_TRANSACTION_TIMESTAMP
  The timestamp when the first transaction was written to the log.
• LAST_TRANSACTION_ID
  The ID of the most recent transaction that was written to this log type with this compression type.
• LAST_TRANSACTION_COMPRESSED_BYTES
  The total number of bytes that were compressed and then written to the log for the most recent transaction, counted after compression.
• LAST_TRANSACTION_UNCOMPRESSED_BYTES
  The total number of bytes before compression for the most recent transaction.
• LAST_TRANSACTION_TIMESTAMP
  The timestamp when the most recent transaction was written to the log.

Thebinary_log_transaction_compression_stats table has no indexes.

TRUNCATE TABLE is permitted for thebinary_log_transaction_compression_stats table.