xref: /sqlite-3.40.0/ext/misc/README.md (revision 4297584d) 
1## Miscellaneous Extensions
2
3This folder contains a collection of smaller loadable extensions.
4See <https://www.sqlite.org/loadext.html> for instructions on how
5to compile and use loadable extensions.
6Each extension in this folder is implemented in a single file of C code.
7
8Each source file contains a description in its header comment.  See the
9header comments for details about each extension.  Additional notes are
10as follows:
11
12  *  **carray.c** &mdash;  This module implements the
13     [carray](https://www.sqlite.org/carray.html) table-valued function.
14     It is a good example of how to go about implementing a custom
15     [table-valued function](https://www.sqlite.org/vtab.html#tabfunc2).
16
17  *  **csv.c** &mdash;  A [virtual table](https://sqlite.org/vtab.html)
18     for reading
19     [Comma-Separated-Value (CSV) files](https://en.wikipedia.org/wiki/Comma-separated_values).
20
21  *  **dbdump.c** &mdash;  This is not actually a loadable extension, but
22     rather a library that implements an approximate equivalent to the
23     ".dump" command of the
24     [command-line shell](https://www.sqlite.org/cli.html).
25
26  *  **json1.c** &mdash;  Various SQL functions and table-valued functions
27     for processing JSON.  This extension is already built into the
28     [SQLite amalgamation](https://sqlite.org/amalgamation.html).  See
29     <https://sqlite.org/json1.html> for additional information.
30
31  *  **memvfs.c** &mdash;  This file implements a custom
32     [VFS](https://www.sqlite.org/vfs.html) that stores an entire database
33     file in a single block of RAM.  It serves as a good example of how
34     to implement a simple custom VFS.
35
36  *  **rot13.c** &mdash;  This file implements the very simple rot13()
37     substitution function.  This file makes a good template for implementing
38     new custom SQL functions for SQLite.
39
40  *  **series.c** &mdash;  This is an implementation of the
41     "generate_series" [virtual table](https://www.sqlite.org/vtab.html).
42     It can make a good template for new custom virtual table implementations.
43
44  *  **shathree.c** &mdash;  An implementation of the sha3() and
45     sha3_query() SQL functions.  The file is named "shathree.c" instead
46     of "sha3.c" because the default entry point names in SQLite are based
47     on the source filename with digits removed, so if we used the name
48     "sha3.c" then the entry point would conflict with the prior "sha1.c"
49     extension.
50
51  *  **unionvtab.c** &mdash; Implementation of the unionvtab and
52     [swarmvtab](https://sqlite.org/swarmvtab.html) virtual tables.
53     These virtual tables allow a single
54     large table to be spread out across multiple database files.  In the
55     case of swarmvtab, the individual database files can be attached on
56     demand.
57
58  *  **zipfile.c** &mdash;  A [virtual table](https://sqlite.org/vtab.html)
59     that can read and write a
60     [ZIP archive](https://en.wikipedia.org/wiki/Zip_%28file_format%29).
61