This page is about using in-memory SQLite databases. ---- 2005-03-25: :memory: doesn't seem to work if using sqlite3_open16(), rather than sqlite3_open(). I assume this is a bug? ---- 2005-03-25: I want to create a database first in memory and then dump it on a file. How can I do this? 2005-07-03: I've written a patch for SQLite 3.2.2 to add the feature you asking for. ---- 2004-09-15: I've written an article about memory databases in combination with PHP: SQLite in- memory databases. ---- 2004-08-08: SQLite would be really useful for me if it supported shared memory databases, so that unlike ':memory', multiple processes could share the same in-memory database. I am currently using Turck MMcache to share data among PHP scripts; if I could use SQLite instead with similar performance it would be really good. 2005-11-02: If you are on Linux, perhaps you could use the shared memory filesystm (tmpfs). It looks just like a normal filesystem, except the Linux kernel stores it all in memory. Some distributions come out of the box with /dev/shm mounted in this way, so you can share memory just by sharing files in this directory. ---- 2003-04-15: The in-memory database is now in the CVS tree, though it is still mostly untested. 2003-05-09: In-memory databases are now a feature of the standard SQLite library. To open an in- memory database, use filename ":memory:". ---- _While connections to on-disk databases should not be carried across a Unix fork(), is there any reason not to do it with an in-memory database?_ (2003-10-21 by drh:) Not that I know of. DK: Of course, when you do the fork() you are creating a new copy of the in-memory db for the child process. So subsequent edits to the db in the child won't show up in the parents copy, and vice-versa. NgPS: Multiple connections to ":memory:" within a single process create a fresh database each time: * (defvar db (sql:connect '(":memory:") :database-type :sqlite :make-default nil :if-exists :new)) DB * (sql:execute-command "create table a (id integer primary key, x varchar)" :database db) T * (sql:execute-command "insert into a values (NULL, 'aaa')" :database db) T * (sql:execute-command "insert into a values (NULL, 'bbb')" :database db) T * (sql:execute-command "insert into a values (NULL, 'ccc')" :database db) T * (sql:query "select * from a" :database db) (("1" "aaa") ("2" "bbb") ("3" "ccc")) * (sql:query "select * from sqlite_master" :database db) (("table" "a" "a" "3" "create table a (id integer primary key, x varchar)")) * (defvar db2 (sql:connect '(":memory:") :database-type :sqlite :make-default nil :if-exists :old)) DB2 * (sql:query "select * from sqlite_master" :database db2) NIL