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PL/pgSQL stored procedure code coverage tool
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PostgreSQL PL/pgSQL stored procedure code coverage Build Status



PL/pgSQL doesn't have much in the way of developer tools, and writing automated tests for stored procedures can be much easier when you know what you haven't tested. Code coverage allows you to see which parts of your code haven't been executed.

Piggly is a tool (written in Ruby, but you can write your tests in any language) to track code coverage of PostgreSQL PL/pgSQL stored procedures. It reports on code coverage to help you identify untested parts of your code.

How Does It Work?

Piggly tracks the execution of PostgreSQL's PL/pgSQL stored procedures by recompiling the stored procedure with instrumentation code. Basically, RAISE WARNING statements notify the client of an execution event (e.g., a branch condition evaluating to true or false). It records these events and generates prettified source code that is annotated with coverage details.


  • Readable and easily-navigable reports (see example)
  • Language agnostic - write your tests in Ruby, Python, Java, SQL scripts etc
  • Branch, block, and loop coverage analysis
  • Instrumenting source-to-source compiler
  • Low test execution overhead
  • Reduced compilation times by use of disk caching
  • Possible to aggregate coverage across multiple runs


  • Not all PL/pgSQL grammar is currently supported, but the grammar is easy to modify
  • Cannot parse nested dollar-quoted strings, eg $A$ ... $B$ ... $B$ ... $A$
  • SQL statements are not instrumented, so their branches (COALESCE, WHERE-clauses, etc) aren't tracked


  • Treetop: gem install treetop
  • The ruby-pg driver: gem install pg
  • The examples require ActiveRecord: gem install activerecord

How to Install

To install the latest from github:

$ git clone git://
$ cd piggly
$ bundle install
$ bundle exec rake spec

$ rake gem
$ gem install pkg/*.gem --no-rdoc --no-ri

To install the latest release:

$ gem install piggly


Your stored procedures must already be loaded in the database. Configure your database connection in a file named config/database.yml relative to where you want to run piggly. You can also specify the -d PATH to an existing configuration file. The contents of the file follow ActiveRecord conventions:

  adapter: postgresql
  database: cookbook
  username: kputnam
  password: secret
  host: localhost

Here we'll add some stored procedures to the database we described above:

$ cat example/proc/*.sql | psql -U kputnam -h localhost cookbook

Note the connection is expected to be named piggly but you may specify the -k DATABASE option to use a different connection name (eg -k development in Rails). See also example/config/database.yml.

Now you are ready to recompile and install your stored procedures. This reads the configuration from ./config/database.yml relative to the current working directory.

$ piggly trace
compiling 5 procedures
Compiling scramble
Compiling scramble
Compiling numberedargs
Compiling snippets
Compiling iterate
tracing 5 procedures

This caches the original version (without instrumentation) in piggly/cache so you can restore them later. Piggly will only recompile procedures that have changed in the database since it last made a copy in piggly/cache.

WARNING: piggly fetches your code from the database and replaces it (in the database) with the instrumented code. If you run piggly trace twice consecutively, the second time will cause an error because you are trying to re-instrument code that has already been instrumented. You need to run piggly untrace or restore your original stored procedures manually before you can trace them again.

Now you're ready to execute your tests. Make sure your connection is configured to log RAISE WARNING messages to a file -- or you can log them to STDERR and redirect that to a file. For instance you might run:

$ ant test 2> messages.txt
$ make test 2> messages.txt

To build the coverage report, have piggly read that file in by executing piggly report < messages.txt, or piggly report -f messages.txt. You don't actually need the intermediate file, you can pipe your test suite directly in like ant test 2>&1 | piggly report.

Once the report is built you can open it in piggly/reports/index.html.

Running the Examples

$ cd piggly
$ bundle install
$ cat example/README

$ ./example/run-tests
compiling 5 procedures
Compiling scramble
Compiling scramble
Compiling numberedargs
Compiling snippets
Compiling iterate
tracing 5 procedures
Loaded suite /home/kputnam/wd/piggly/example/test/iterate_test
Finished in 0.199236 seconds.

6 tests, 6 assertions, 0 failures, 0 errors, 0 skips

Test run options: --seed 25290
clearing previous coverage
storing coverage profile
creating index
creating reports
reporting coverage for scramble
reporting coverage for scramble
reporting coverage for numberedargs
reporting coverage for snippets
reporting coverage for iterate: +0.0% block, +0.0% branch, +0.0% loop
restoring 5 procedures
OK, view /home/kputnam/wd/piggly/example/piggly/reports/index.html

$ ls -alh example/reports/index.html
-rw-r--r-- 1 kputnam kputnam 1.4K 2010-04-28 11:21 example/reports/index.html

Bugs & Issues

Please report any issues or feature requests on the github tracker.

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