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This topic lists limitations and maximums for Greenplum Database full text search objects.
The current limitations of Greenplum Database's text search features are:
- The tsvector and tsquery types are not supported in the distribution key for a Greenplum Database table
- The length of each lexeme must be less than 2K bytes
- The length of a tsvector (lexemes + positions) must be less than 1 megabyte
- The number of lexemes must be less than 264
- Position values in tsvector must be greater than 0 and no more than 16,383
- No more than 256 positions per lexeme
- The number of nodes (lexemes + operators) in a tsquery must be less than 32,768
For comparison, the PostgreSQL 8.1 documentation contained 10,441 unique words, a total of 335,420 words, and the most frequent word "postgresql" was mentioned 6,127 times in 655 documents.
Another example — the PostgreSQL mailing list archives contained 910,989 unique words with 57,491,343 lexemes in 461,020 messages.