sqlite/ext/misc/README.md

## Miscellaneous Extensions

This folder contains a collection of smaller loadable extensions.
See <https://www.sqlite.org/loadext.html> for instructions on how
to compile and use loadable extensions.
Each extension in this folder is implemented in a single file of C code.

Each source file contains a description in its header comment.  See the
header comments for details about each extension.  Additional notes are
as follows:

  *  **carray.c** &mdash;  This module implements the
     [carray](https://www.sqlite.org/carray.html) table-valued function.
     It is a good example of how to go about implementing a custom
     [table-valued function](https://www.sqlite.org/vtab.html#tabfunc2).

  *  **csv.c** &mdash;  A [virtual table](https://sqlite.org/vtab.html)
     for reading 
     [Comma-Separated-Value (CSV) files](https://en.wikipedia.org/wiki/Comma-separated_values).

  *  **dbdump.c** &mdash;  This is not actually a loadable extension, but
     rather a library that implements an approximate equivalent to the
     ".dump" command of the
     [command-line shell](https://www.sqlite.org/cli.html).

  *  **json1.c** &mdash;  Various SQL functions and table-valued functions
     for processing JSON.  This extension is already built into the
     [SQLite amalgamation](https://sqlite.org/amalgamation.html).  See
     <https://sqlite.org/json1.html> for additional information.

  *  **memvfs.c** &mdash;  This file implements a custom
     [VFS](https://www.sqlite.org/vfs.html) that stores an entire database
     file in a single block of RAM.  It serves as a good example of how
     to implement a simple custom VFS.

  *  **rot13.c** &mdash;  This file implements the very simple rot13()
     substitution function.  This file makes a good template for implementing
     new custom SQL functions for SQLite.

  *  **series.c** &mdash;  This is an implementation of the
     "generate_series" [virtual table](https://www.sqlite.org/vtab.html).
     It can make a good template for new custom virtual table implementations.

  *  **shathree.c** &mdash;  An implementation of the sha3() and
     sha3_query() SQL functions.  The file is named "shathree.c" instead
     of "sha3.c" because the default entry point names in SQLite are based
     on the source filename with digits removed, so if we used the name
     "sha3.c" then the entry point would conflict with the prior "sha1.c"
     extension.

  *  **unionvtab.c** &mdash; Implementation of the unionvtab and
     [swarmvtab](https://sqlite.org/swarmvtab.html) virtual tables.
     These virtual tables allow a single
     large table to be spread out across multiple database files.  In the
     case of swarmvtab, the individual database files can be attached on
     demand.

  *  **zipfile.c** &mdash;  A [virtual table](https://sqlite.org/vtab.html)
     that can read and write a 
     [ZIP archive](https://en.wikipedia.org/wiki/Zip_%28file_format%29).