Hussein Nasser talks about rows per page. Peter Zaitsev discusses Postgres TV. Topics include TOAST, data storage and limitations, LZ-Boys compression, toast limitations in PostgreSQL, optimizing column ordering, and exploring the impact of medium-size text in a database.
Postgres allows storing large amounts of data in a single column, benefiting sorting and storage efficiency.
Toast in Postgres splits large values into smaller chunks and stores pointers, enabling efficient storage and performance optimization.
Deep dives
Storing Large Data in Postgres
Postgres provides the ability to store large amounts of data in a single column, allowing up to one gigabyte of data in a single cell. This feature is beneficial when working with large values and allows for efficient sorting and storage.
Understanding Toast and Page Layout
Toast in Postgres is a mechanism that handles the storage of large values that cannot fit in a single page. By splitting the data into smaller chunks and storing pointers to each chunk, Postgres can reconstruct the complete value when needed. Understanding the internal layout of pages and the headers of tuples helps in optimizing storage and performance.
Compression and Limitations of Toast
Toast in Postgres also supports compression to save storage space. Automatic compression is applied to large values before storing them in the toast table. However, there are limitations to consider, such as a maximum size limit of one gigabyte for a value and the restriction that toast is not applied before indexing, which may impact performance. Efficient column Tetris techniques can optimize storage efficiency, and considering the use of a separate table for medium-sized text fields can improve query efficiency.