MQL, the Metaweb Query Language
This repository contains the original implementation of the Metaweb Query Language, written in Python.
Building / Using MQL
Even though MQL is written in Python, this particular version of it requires Bazel to operate properly. You can build the simple command-line MQL query tool like so:
[¬º-°]¬ bazel build :mqlbin
INFO: Analyzed target //:mqlbin (6 packages loaded, 36 targets configured).
INFO: Found 1 target...
Target //:mqlbin up-to-date:
bazel-out/k8-py2-fastbuild/bin/mqlbin
INFO: Elapsed time: 0.771s, Critical Path: 0.02s
INFO: 0 processes.
INFO: Build completed successfully, 1 total action
Then, it can be executed out of the bazel build directory:
IMPORTANT! This will only work if you have properly you need to have an instance of graphd running and it needs to be properly bootstrapped for MQL (see below).
[¬º-°]¬ bazel-out/k8-py2-fastbuild/bin/mqlbin --graphd_addr=localhost:8100 --mqlcmd=read '{"id": "/type/object/type", "guid": null}'
<logs...>
MQLResult(result={'guid': '#d119a8c0400062d1800000000000000c', 'id': '/type/object/type'}, cost=defaultdict(<type 'float'>, {'pr': 0.0, 'va': 38742.0, 'tu': 22.0, 'in': 3975.0, 'ir': 0.0, 'tr': 23.0, 'ts': 0.0, 'iw': 0.0, 'te': 26.0, 'mql_utime': 0.047658000000000006, 'mql_dbreqs': 11, 'dw': 0.0, 'tg': 0.030711889266967773, 'tf': 0.04290890693664551, 'pf': 0.0, 'mql_rtime': 1.1784470081329346, 'dr': 5619.0, 'gqr': 0, 'mql_stime': 0.0009940000000000018}), dateline=None, cursor=None)
Bootstrapping a graphd for MQL
PyMQL comes with a graphd bootstrap program that you can use to bootstrap an empty graphd for use with MQL. The bootstrap program itself writes the set of core types required for MQL to operate.
First, ensure you have a graphd running:
[¬º-°]¬ git clone https://github.com/google/graphd
Cloning into 'graphd'...
remote: Enumerating objects: 1259, done.
remote: Total 1259 (delta 0), reused 0 (delta 0), pack-reused 1259
Receiving objects: 100% (1259/1259), 2.57 MiB | 14.95 MiB/s, done.
Resolving deltas: 100% (482/482), done.
[¬º-°]¬ cd graphd
[¬º-°]¬ bazel build graphd
...(graphd builds)
Target //graphd:graphd up-to-date:
bazel-bin/graphd/graphd
INFO: Elapsed time: 29.584s, Critical Path: 0.87s
INFO: 373 processes: 373 linux-sandbox.
INFO: Build completed successfully, 377 total actions
[¬º-°]¬ bazel-bin/graphd/graphd -d /tmp/data-dir -p /tmp/graphd.pid -n
<graphd is now running in the foreground>
In another terminal, run the bootstrap:
[¬º-°]¬ ./bazel-out/k8-py2-fastbuild/bin/bootstrap/bootstrap --load bootstrap/otg.bootstrap
The bootstrap takes a few minutes to run and you'll see lots of
graphd.request.start and graphd.request.end lines. This is normal.
After this is done, you can run MQL queries via mqlbin.
History
This code was originally authored by Tim Sturge, then maintained by Warren Harris after his departure.
Dime ("2 MQL's") was the implementation written by Warren in OCaml that offered significant improvements over this initial implementation. However, when Metaweb was acquired by Google nearing the end of the productionization of Dime, it was only used partially until Freebase was turned down a few years later. In the meantime, Warren had gone on to develop other tools used during the early days of the Knowledge Graph projects at Google.
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