PostgreSQL Reference Manual - Volume 2 - Programming Guide by The PostgreSQL Global Development Group Paperback (6"x9"), 408 pages ISBN 0954612035 RRP £19.95 ($34.95) Sales of this book support the PostgreSQL project! Get a printed copy>>>

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2.1 Introduction

All large objects are placed in a single system table called pg_largeobject. PostgreSQL also supports a storage system called “TOAST” that automatically stores values larger than a single database page into a secondary storage area per table. This makes the large object facility partially obsolete. One remaining advantage of the large object facility is that it allows values up to 2 GB in size, whereas TOASTed fields can be at most 1 GB. Also, large objects can be randomly modified using a read/write API that is more efficient than performing such operations using TOAST.