Postgres 19 Compression: from pglz to LZ4
Summary
The article explains Postgres 19's planned default TOAST compression change from pglz to LZ4 and how compression works across table storage, TOAST, and indexes. It provides historical context, details on the varlena format, and a practical view of compression decisions and measurements, including when data compresses well or poorly. It also discusses the tradeoffs between compression speed and ratio and the impact on indexing.