Supplied typenames are not used by FTS or the SQLite core for any The CREATE VIRTUAL TABLE statement, then a datatype name may be optionally If column names are explicitly provided for the FTS table as part of May be passed a list of comma separated column names. The virtual table module arguments mayīe left empty, in which case an FTS table with a single user-definedĬolumn named "content" is created. The USING keyword, is either "fts3" or "fts4". Like other virtual table types, new FTS tables are created using aĬREATE VIRTUAL TABLE statement. Versions of SQLite is important, then FTS3 will usually serve just as well. More disk space than FTS3, though only a percent of two in most cases.įor newer applications, FTS4 is recommended though if compatibility with older Other hand, in the absence of a matchinfo=fts3 directive FTS4 requires a little FTS4 also offers the enhanced matchinfo() outputs whichĬan be useful in ranking the results of a MATCH operation. Sometimes significantly faster than FTS3, even orders of magnitude fasterĭepending on the query, though in the common case the performance of the two Which module, FTS3 or FTS4, should you use in your application? FTS4 is The enhancements for FTS4 were added with SQLite version 3.7.4 Options) allowing data to be stored in a compressedįTS3 has been available since SQLite version 3.5.0 () The overhead may be reduced by specifying theĭirective "matchinfo=fts3" as part of the FTS4 tableĭeclaration, but this comes at the expense of sacrificing some of theįTS4 provides hooks (the compress and uncompress
Is 1-2% or less, but may be as high as 10% if the documents stored in theįTS table are very small. Optimizations and extra matchinfo() options, FTS4 tables may consume moreĭisk space than the equivalent table created using FTS3.
Shadow tables in order to support the performance
Very common (present in a large percentage of table rows).įTS4 supports some additional options that may used with the matchinfo()īecause it stores extra information on disk in two new Improve the performance of full-text queries that contain terms that are The differences are:įTS4 contains query performance optimizations that may significantly
#SQLITE SUBSTRING CODE#
They share most of their code in common,Īnd their interfaces are the same. Table took just under 31 minutes to populate, versus 25 for the ordinaryįTS3 and FTS4 are nearly identical. Hardware configuration used to perform the SELECT queries above, the FTS3 The FTS3 table consumes around 2006 MB onĭisk compared to just 1453 MB for the ordinary table. Selects only those rows that contain "linux" as a discrete token. Or "EnterpriseLinux" (as it happens, the Enron E-Mail Dataset does notĪctually contain any such terms), whereas the MATCH query on the FTS3 table The LIKE query matches rows that contain terms such as "linuxophobe" Of course, the two queries above are not entirely equivalent. SELECT count(*) FROM enrondata2 WHERE content LIKE '%linux%' /* 22.5 seconds */ SELECT count(*) FROM enrondata1 WHERE content MATCH 'linux' /* 0.03 seconds */ Is inserted into both an FTS table and an ordinary SQLite table One or more words (hereafter "tokens"), even if the tableįor example, if each of the 517430 documents in the The full-text indexĪllows the user to efficiently query the database for all rows that contain The FTS3 and FTS4 extension modules allows users to create special tables with aīuilt-in full-text index (hereafter "FTS tables"). Portions of the original FTS3 code were contributed to the SQLite projectĭeveloped and maintained as part of SQLite. Issues with these older modules and their use should be avoided. This article describes the deployment and usage of FTS3 and FTS4.įTS1 and FTS2 are obsolete full-text search modules for SQLite. Matches those terms considering the operators and groupings the user has
Phrase, and the full-text query system finds the set of documents that best Of terms, perhaps connected by a binary operator or grouped together into a With documents placed on the World Wide Web". Way to describe full-text searches is "what Google, Yahoo, and Bing do FTS3 and FTS4 are SQLite virtual table modules that allows users to performįull-text searches on a set of documents.
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