PostgreSQL
12.11. Limitations
The current limitations of PostgreSQL’s text search features are:
-
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
tsvectormust be greater than 0 and no more than 16,383 -
The match distance in a
<`N>` (FOLLOWED BY)tsqueryoperator cannot be more than 16,384 -
No more than 256 positions per lexeme
-
The number of nodes (lexemes + operators) in a
tsquerymust 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 “[.quote]#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.
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