PGLoader
pgloader is a data loading tool for PostgreSQL, using the COPY
command.
Its main advantage over just using COPY
or \copy
, and over using a
Foreign Data Wrapper, is its transaction behaviour, where pgloader
will keep a separate file of rejected data, but continue trying to
copy
good data in your database.
The default PostgreSQL behaviour is transactional, which means that any erroneous line in the input data (file or remote database) will stop the entire bulk load for the table.
pgloader also implements data reformatting, a typical example of that
being the transformation of MySQL datestamps 0000-00-00
and
0000-00-00 00:00:00
to PostgreSQL NULL
value (because our calendar
never had a year zero).
Versioning
The pgloader version 1.x from a long time ago was developed in TCL
.
When faced with maintaining that code, the new emerging development
team (hi!) picked python
instead because that made sense at the
time. So pgloader version 2.x were in python.
The current version of pgloader is the 3.x series, which is written in Common Lisp for better development flexibility, runtime performance, and support of real threading.
The versioning is now following the Emacs model, where any X.0 release
number means you're using a development version (alpha, beta, or release
candidate). The next stable versions are going to be 3.1
then 3.2
etc.
When using a development snapshot rather than a released version the version number includes the git hash (in its abbreviated form):
-
pgloader version "3.0.99"
Release candidate 9 for pgloader version 3.1, with a git tag named
v3.0.99
so that it's easy to checkout the same sources as the released code. -
pgloader version "3.0.fecae2c"
Development snapshot again git hash
fecae2c
. It's possible to have the same sources on another setup with using the git commandgit checkout fecae2c
. -
pgloader version "3.1.0"
Stable release.
LICENCE
pgloader is available under The PostgreSQL Licence.
INSTALL
pgloader is now a Common Lisp program, tested using the SBCL (>= 1.1.14) and Clozure CL implementations with Quicklisp.
$ apt-get install sbcl libsqlite3-dev make curl
$ cd /path/to/pgloader
$ make pgloader
$ ./build/bin/pgloader --help
You can also fetch pre-made binary packages at pgloader.io.
Testing a new feature
Being a Common Lisp program, pgloader is able to upgrade itself at run
time, and provides the command-line option --self-upgrade
that just does
that.
If you want to test the current repository version (or any checkout really), it's possible to clone the sources then load them with an older pgloader release:
$ /usr/bin/pgloader --version
pgloader version "3.0.99"
compiled with SBCL 1.1.17
$ git clone https://github.com/dimitri/pgloader.git /tmp/pgloader
$ /usr/bin/pgloader --self-upgrade /tmp/pgloader --version
Self-upgrading from sources at "/tmp/pgloader/"
pgloader version "3.0.fecae2c"
compiled with SBCL 1.1.17
Here, the code from the git clone will be used at run-time. Self-upgrade is done first, then the main program entry point is called again with the new coded loaded in.
The pgloader.lisp script
Now you can use the #!
script or build a self-contained binary executable
file, as shown below.
./pgloader.lisp --help
Each time you run the pgloader
command line, it will check that all its
dependencies are installed and compiled and if that's not the case fetch
them from the internet and prepare them (thanks to Quicklisp). So please
be patient while that happens and make sure we can actually connect and
download the dependencies.
Build Self-Contained binary file
The Makefile
target pgloader
knows how to produce a Self Contained
Binary file for pgloader, named pgloader.exe
:
$ make pgloader
By default, the Makefile
uses SBCL to compile your
binary image, though it's possible to also build using
CCL.
$ make CL=ccl pgloader
Note that the Makefile
uses the --compress-core
option when using SBCL,
that should be enabled in your local copy of SBCL
. If that's not the case,
it's probably because you did compile and install SBCL
yourself, so that
you have a decently recent version to use. Then you need to compile it with
the --with-sb-core-compression
option.
You can also remove the --compress-core
option that way:
$ make COMPRESS_CORE=no pgloader
The --compress-core
is unique to SBCL, so not used when CC
is different
from the sbcl
value.
The make pgloader
command when successful outputs a ./build/bin/pgloader
file for you to use.
Usage
Give as many command files that you need to pgloader:
$ ./build/pgloader.exe --help
$ ./build/pgloader.exe <file.load>
See the documentation file pgloader.1.md
for details. You can compile that
file into a manual page or an HTML page thanks to the pandoc
application:
$ apt-get install pandoc
$ pandoc pgloader.1.md -o pgloader.1
$ pandoc pgloader.1.md -o pgloader.html