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:
dbdump.c — 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.
json1.c — Various SQL functions and table-valued functions for processing JSON. This extension is already built into the SQLite amalgamation. See https://sqlite.org/json1.html for additional information.
memvfs.c — This file implements a custom VFS 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 — 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 — This is an implementation of the "generate_series" virtual table. It can make a good template for new custom virtual table implementations.
shathree.c — 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 — Implementation of the unionvtab and swarmvtab 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.