1. Introduction

+ +

A virtual table is an object that presents an SQL table +interface but which is not stored in the database file, at least +not directly. The virtual table mechanism is a feature +of SQLite that allows SQLite to access and manipulate resources +other than bits in the database file using the powerful SQL +query language. + +

+The table below lists a few of the virtual tables implementations +available for SQLite. Developers can deploy these virtual tables +in their own applications, or use the implementations shown below +as templates for writing their own virtual tables. + +

+The list below is not exhaustive. +Other virtual table implementation exist in the SQLite source tree +and elsewhere. +The list below tries to capture the more interesting virtual table +implementations. + + + +

2. Virtual Tables

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Name	Description
approximate_match	A demonstration of how to use a virtual table to implement + approximate string matching.
bytecode	A table-valued function that shows the bytecodes of a prepared + statement.
carray	A table-valued function that allows a C-language array of integers, + doubles, or strings to be used as table in a query.
closure	Compute the transitive closure of a set.
completion	Suggests completions for partially-entered words during interactive + SQL input. Used by the CLI to help implement tab-completion.
csv	A virtual table that represents a comma-separated-value or CSV file + (RFC 4180) as a read-only + table so that it can be used as part of a larger query.
dbstat	Provides information about the purpose and use of each page in a + database file. Used in the implementation of the + sqlite3_analyzer utility program.
files_of_checkin	Provides information about all files in a single check-in in the + Fossil version control system. This + virtual table is not part of the SQLite project but is included because + it provides an example of how to use virtual tables and because it is + used to help version control the SQLite sources.
fsdir	A table-valued function returning one row for each file in a + selected file hierarchy of the host computer. Used by the + CLI to help implement the .archive command.
FTS3	A high-performance full-text search index.
FTS5	A higher-performance full-text search index
generate_series	A table-valued function returning a sequence of + integers, modeled after the table-valued function by the same + name in PostgreSQL.
json_each	A table-valued function for decomposing a JSON string.
json_tree	A table-valued function for decomposing a JSON string.
OsQuery	Hundreds of virtual tables that publish various aspects of the + host computer, such as the process table, user lists, active network + connections, and so forth. + OsQuery is a separate project, started by Facebook, hosted on + GitHub, and intended for + security analysis and intrusion detection + OsQuery is not a part of the SQLite project, but is included in this + list because it demonstrates how the SQL language and the + SQLite virtual table mechanism + can be leveraged to provide elegant solutions + to important real-world problems.
pragma	Built-in table-valued functions that return the results of PRAGMA + statements for use within ordinary SQL queries.
RTree	An implementation of the Guttmann R*Tree spatial index idea.
spellfix1	A virtual table that implements a spelling correction engine.
sqlite_btreeinfo	This experimental table-valued function provides information about + a single B-tree in a database file, such as the depth, and estimated + number of pages and number of entries, and so forth.
sqlite_dbpage	Key/value store for the raw database file content. The key is the + page number and the value is binary page content.
sqlite_memstat	Provides SQL access to the sqlite3_status64() and + sqlite3_db_status() interfaces.
sqlite_stmt	A table-valued function containing one row for each + prepared statement associated with an open database connection.
swarmvtab	An experimental module providing on-demand read-only access to + multiple tables spread across multiple databases, via a single + virtual table abstraction.
tables_used	A table-valued function that shows the tables and indexes that + are accessed by a prepared statement.
tclvar	Represents the global variables of a + TCL Interpreter as an SQL + table. Used as part of the SQLite test suite.
templatevtab	A template virtual table implementation useful as a starting point + for developers who want to write their own virtual tables
unionvtab	An experimental module providing on-demand read-only access to + multiple tables spread across multiple databases, via a single + virtual table abstraction.
vfsstat	A table-valued function which, in combination with a + co-packaged VFS shim provides information on the number of + system calls performed by SQLite.
vtablog	A virtual table that prints diagnostic information + on stdout when its key methods are invoked. Intended for + interactive analysis and debugging of virtual table interfaces.
wholenumber	A virtual table returns all integers between 1 and 4294967295.
zipfile	Represent a + ZIP Archive + as an SQL table. Works for both reading and writing. Used by + the CLI to implement the ability to read and write ZIP Archives.

This page last modified on 2023-05-01 21:49:55 UTC

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