Tale of the PostgreSQL TOAST Table
PostgreSQL’s default page size is 8 KB. PostgreSQL does not allow row/tuple to span multiple pages. TOAST (The Oversized-Attribute Storage Technique) is a mechanism PostgreSQL uses to keep tuple from exceeding the size of a default page size, so the block size is a hard upper limit on row size.
To allow user tables to have rows wider than this, the TOAST mechanism breaks up wide field values into smaller pieces, which are stored “out of line” in a TOAST table associated with the user table.
In this presentation, Shailesh Rangani, Director and Global Practice Leader of PostgreSQL Services, Datavail, covers various aspects of the TOAST tables, what are the storage options for storing TOAST table and its impact, and what is the impact on the performance on text size of the column. Rangani also details how to query information related to TOAST table from PostgreSQL metadata.
In this session, you will learn:
- Introduction to the TOAST table mechanism
- TOAST table storage strategy options
- Optimizing query time with the TOAST table storage strategy
- How to find information about TOAST tables using PostgreSQL metadata
- Impact of Texts Size on PostgreSQL Performance
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