Ddtrace

With `0.19.0` we have decided to disable the tracing of `dbapi2` `fetchone()`/`fetchmany()`/`fetchall()` methods by default.

This change effects all integrations which rely on the `dbapi2` API, including `psycopg2`, `mysql`, `mysqldb`, `pymysql`, and `sqlite3`.

We have introduced this change to reduce the noise added to traces from having these methods (mostly `fetchone()`) traced by default.

With `fetchone()` enabled the traces received can get very large for large result sets, the resulting traces either become difficult to read or become too large causing issues when flushing to the trace agent, potentially causing traces to be dropped.

To re-enable the tracing of these methods you can either configure via the environment variable `DD_DBAPI2_TRACE_FETCH_METHODS=true` or manually via:

python
from ddtrace import config
config.dbapi2.trace_fetch_methods = True


Changes
Bugs
[dbapi2] disable fetchone/fetchmany/fetchall tracing by default (780)
[opentracing] Fixing context provider imports for scope manager (771 -- thanks Maximilien-R)

Enhancements
[tests] test python setup.py sdist and twine check on build (782)
[core] Add API to configure Trace Search (781)
[core] Enable priority sampling by default (774)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.18.0...v0.19.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/32?closed=1).
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New Integrations

* [molten] Add molten support (685)

Bug Fixes

* [aws] Blacklist arguments stored as tags (761)
* [psycopg2] Fix composable query tracing (736)

Improvements

* [aiohttp] Add HTTP method to the root span resource (652 -- thanks k4nar)
* [aws]Flatten span tag names (768)
* [opentracer] Set global tags (764)
* [core] add six and replace custom compat functions (751)
* [config] make IntegrationConfig an AttrDict (742)
* [tests] remove unused monkey.py test file (760)
* [tests] fix linting in test files (752)
* [psycopg2] fix linting issues (749)
* [tests] have most tests use pytest test runner (748)
* [tests] Provide default implementation of patch test methods (747)
* [tests] run flake8 on all test files (745)
* [tests] Add patch mixin and base test case (721)
* [tests] Add Subprocess TestCase (720)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.17.1...v0.18.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/30?closed=1).
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This release includes the removal of service sending, this should resolve many of the 400s that are being returned from the Agent resulting in an unfriendly `ERROR` message and giving the impression that the tracer is failing. (757)

Improvements
- [core] Make writing services a no-op (735)
- [tests] upgrade flake8 to 3.5.0 (743)
- remove flake8 ignores and fix issues (744)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.17.0...v0.17.1) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/31?closed=1).
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New features
- [redis] add support for redis 3.0.0 (716)
- [core] Allow DD_AGENT_HOST and DD_TRACE_AGENT_PORT env variables (708)
- [core] Add global tracer tags (702)
- [core] Trace http headers (647)

Improvements
- [docs] add Flask configuration documentation (734)
- Add long_description to setup.py (728)
- [tests] pin version of redis-py-cluster for 'tox -e wait' (725)
- [requests] Add another split_by_domain test (713)
- [docs] Add kombu references (711)
- [ci] Use small circleci resource class for all jobs (710)
- [requests] patch Session.send instead of Session.request (707)
- [ci] reorganize CircleCI workflows (705)
- [elasticsearch] add support for elasticsearch{1,2,5} packages (701)
- [tests] add base test case classes and rewrite tracer tests (689)
- [dbapi] Trace db fetch and session methods (664)

Bugfixes
- [elasticsearch] add alias for default _perform_request (737)
- [tests] Pin pytest to 3.x.x and redis to 2.10.x for rediscluster (727)
- [django] Use a set instead of list for cache_backends to avoid duplicates (726 -- thanks wenbochang)
- [tests] fix broken redis check (722)
- [docs] Fix broken flask link (712)
- [mongodb] Fix pymongo query metadata (706)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.16.0...v0.17.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/29?closed=1).
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New Integrations
* [jinja2] Add jinja2 integration (649 -- thanks mgu)
* [kombu] add Kombu integration (515 -- thanks tebriel)
* [grpc] Add grpc client support. (641)
* [gevent] Support gevent 1.3 (663)
* [flask] rewrite Flask integration (667)

Bug Fixes
* [mysqldb] Fix mysqldb monkey patch (623 -- thanks benjamin-lim)
* [requests] exclude basic auth from service name (646 -- thanks snopoke)

Improvements
* [core] Add IntegrationConfig helper class (684)
* [core] add support for integration span hooks (679)
* [httplib, requests] Sanitize urls in span metadata (688)
* [tests] ensure we are running tests.contrib.test_utils (678)
* [celery] [bottle] Add span type information for celery and bottle. (636)
* [ci] Reorganize autopatch test calls (670)
* [core] initial support for partial flushes (668)
* [django] Remove query from django db span's tag sql.query (659)
* [tests] Make CI faster by disabling dist and install in autopatching tests (654)
* [core] Trace http headers (647)
* [django] Infer span resource name when internal error handler is used (645)
* [elasticsearch] Make constant organization consistent with other integrations (628)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.15.0...v0.16.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/28?closed=1).

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**New integrations**

- Add [rediscluster](https://pypi.org/project/redis-py-cluster/) integration (#533, 637)
- Add [Vertica](https://github.com/vertica/vertica-python) Integration (#634)

**Bug fixes**

- [django] Fix minimum Django version for user.is_authenticated property (626 -- thanks browniebroke)

**Improvements**

- [celery] Add retry reason metadata to spans (630)
- [core] Update config to allow configuration before patching (650)
- [core] Add Tracer API to retrieve the root Span (625)
- [core] Fixed `HTTPConnection` leaking (542 -- thanks mackeyja92)
- [django] Allow Django cache to be seen as a different service. (629)
- [gevent] Patch modules on first import (632)
- [gevent] Add support for gevent.pool.Pool and gevent.pool.Group (600)
- [redis] Removed unused tag (627)
- [requests] Patch modules on first import (632)
- [tests] Add Span.span_type tests (633)
- [tests] Update the integrations libraries versions to the latest possible. (607)
- [tests] CircleCI run tests in the new alpine-based test runner (638)
- [tests] Add test cases for API._put (640)
- [tests] Skip flaky TestWorkers.test_worker_multiple_traces test case (643)
- [tests] Remove tests for not supported gevent 1.3 (644)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.14.1...v0.15.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/25?closed=1).
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