Package: tap-mssql
pipelinewise-tap-mssqlSingertap that extracts data from amssqldatabase and produces JSON-formatted data following theSinger spec.This is aPipelineWisecompatible tap connector.How to use itThe recommended method of running this tap is to use it fromPipelineWise. When running it from PipelineWise you don't need to configure this tap with JSON files and most of things are automated. Please check the related documentation atTap mssqlIf you want to run thisSinger Tapindependently please read further.UsageThis section dives into basic usage oftap-mssqlby walking through extracting
data from a table. It assumes that you can connect to and read from a mssql
database.InstallFirst, make sure Python 3 is installed on your system or follow these
installation instructions forMacorUbuntu.It's recommended to use a virtualenv:python3-mvenvvenvpipinstalltap-mssqlorpython3-mvenvvenv.venv/bin/activatepipinstall--upgradepippipinstalltap-mssqlAdditional OS X RequirementsIn the event you encounter install issues on OS X statingfatal error: 'sqlfront.h' file not found, install FreeTDS with SQL Server compatibility:Download the latest version fromFreeTDSExtract and run./configure --enable-msdblibRunmake && make installHave a source databaseThere's some important business data siloed in this mssql database -- we need to
extract it. Here's the table we'd like to sync:mssql> select * from example_db.animals;
+----|----------|----------------------+
| id | name     | likes_getting_petted |
+----|----------|----------------------+
|  1 | aardvark |                    0 |
|  2 | bear     |                    0 |
|  3 | cow      |                    1 |
+----|----------|----------------------+
3 rows in set (0.00 sec)Create the configuration fileCreate a config file containing the database connection credentials, e.g.:{"host":"localhost","database":"db","port":"3306","user":"root","password":"password"}Recommended optional settings"use_date_datatype": true- This will emit true timestamps and handle the time datatype."use_singer_decimal": true- This will help avoid numeric rounding issues emitting as a string with a format of singer.decimal."cursor_array_size": 10000- This will help speed up extracts over a WAN or low latency network. The default is 1.Windows Authentication is available! Don't provide a user or password and pymssql will use the user that is running the process on windows to login.
e.g.:{"host":"localhost","database":"db"}Optional:To filter the discovery to a particular schema within a database. This is useful if you have a large number of schemas and wish to speed up the discovery.{"filter_dbs":"your database schema name"}Optional:To emit a date as a date without a time component or time without an UTC offset. This is helpful to avoid time conversions or to just work with a date datetype in the target database. If this boolean config item is not set, the default behaviour isfalsei.e. emit date datatypes as a datetime. It is recommended to set this on if you have time datetypes and are having issues uploading into into a target database.{"use_date_datatype":true}Optional:Set the version of TDS to use when communicating with MS SQL Server (the default is 7.3). This is used by pymssql with connecting and fetching data from SQL Server databases. See thepymssqldocumentation andFreeTDSdocumentation for more details.{"tds_version":"7.3"}Optional:The characterset for the database / source system. The default isutf8, however older databases might use a charactersets likecp1252for the encoding. If you have errors with aUnicodeDecodeError: 'utf-8' codec can't decode byte ....then a solution is examine the characterset of the source database / system and make an appropriate substitution for utf8 like cp1252.{"characterset":"utf8"}These are the same basic configuration properties used by the mssql command-line
client (mssql).Optional:To emit all numeric values as strings and treat floats as string data types for the target, set use_singer_decimal to true. The resulting SCHEMA message will contain an attribute in additionalProperties containing the scale and precision of the discovered property:"property":{"inclusion":"available","format":"singer.decimal","type":["null","number"],"additionalProperties":{"scale_precision":"(12,0)"}Usage:{"use_singer_decimal":true}Optional:A numeric setting adjusting the internal buffersize. The common query tuning scenario is for SELECT statements that return a large number of rows over a slow network. Increasing arraysize can improve performance by reducing the number of round-trips to the database. However increasing this value increases the amount of memory required.{"cursor_array_size":10000,}Discovery modeThe tap can be invoked in discovery mode to find the available tables and
columns in the database:$tap-mssql--configconfig.json--discoverA discovered catalog is output, with a JSON-schema description of each table. A
source table directly corresponds to a Singer stream.{"streams":[{"tap_stream_id":"example_db-animals","table_name":"animals","schema":{"type":"object","properties":{"name":{"inclusion":"available","type":["null","string"],"maxLength":255},"id":{"inclusion":"automatic","minimum":-2147483648,"maximum":2147483647,"type":["null","integer"]},"likes_getting_petted":{"inclusion":"available","type":["null","boolean"]}}},"metadata":[{"breadcrumb":[],"metadata":{"row-count":3,"table-key-properties":["id"],"database-name":"example_db","selected-by-default":false,"is-view":false}},{"breadcrumb":["properties","id"],"metadata":{"sql-datatype":"int(11)","selected-by-default":true}},{"breadcrumb":["properties","name"],"metadata":{"sql-datatype":"varchar(255)","selected-by-default":true}},{"breadcrumb":["properties","likes_getting_petted"],"metadata":{"sql-datatype":"tinyint(1)","selected-by-default":true}}],"stream":"animals"}]}Field selectionIn sync mode,tap-mssqlconsumes the catalog and looks for tables and fields
have been marked asselectedin their associated metadata entries.Redirect output from the tap's discovery mode to a file so that it can be
modified:$tap-mssql-cconfig.json--discover>properties.jsonThen editproperties.jsonto make selections. In this example we want theanimalstable. The stream's metadata entry (associated with"breadcrumb": [])
gets a top-levelselectedflag, as does its columns' metadata entries. Additionally,
we will mark theanimalstable to replicate using aFULL_TABLEstrategy. For more,
information, seeReplication methods and state file.[{"breadcrumb":[],"metadata":{"row-count":3,"table-key-properties":["id"],"database-name":"example_db","selected-by-default":false,"is-view":false,"selected":true,"replication-method":"FULL_TABLE"}},{"breadcrumb":["properties","id"],"metadata":{"sql-datatype":"int(11)","selected-by-default":true,"selected":true}},{"breadcrumb":["properties","name"],"metadata":{"sql-datatype":"varchar(255)","selected-by-default":true,"selected":true}},{"breadcrumb":["properties","likes_getting_petted"],"metadata":{"sql-datatype":"tinyint(1)","selected-by-default":true,"selected":true}}]Sync modeWith a properties catalog that describes field and table selections, the tap can be invoked in sync mode:$tap-mssql-cconfig.json--propertiesproperties.jsonMessages are written to standard output following the Singer specification. The
resultant stream of JSON data can be consumed by a Singer target.{"value":{"currently_syncing":"example_db-animals"},"type":"STATE"}{"key_properties":["id"],"stream":"animals","schema":{"properties":{"name":{"inclusion":"available","maxLength":255,"type":["null","string"]},"likes_getting_petted":{"inclusion":"available","type":["null","boolean"]},"id":{"inclusion":"automatic","minimum":-2147483648,"type":["null","integer"],"maximum":2147483647}},"type":"object"},"type":"SCHEMA"}{"stream":"animals","version":1509133344771,"type":"ACTIVATE_VERSION"}{"record":{"name":"aardvark","likes_getting_petted":false,"id":1},"stream":"animals","version":1509133344771,"type":"RECORD"}{"record":{"name":"bear","likes_getting_petted":false,"id":2},"stream":"animals","version":1509133344771,"type":"RECORD"}{"record":{"name":"cow","likes_getting_petted":true,"id":3},"stream":"animals","version":1509133344771,"type":"RECORD"}{"stream":"animals","version":1509133344771,"type":"ACTIVATE_VERSION"}{"value":{"currently_syncing":"example_db-animals","bookmarks":{"example_db-animals":{"initial_full_table_complete":true}}},"type":"STATE"}{"value":{"currently_syncing":null,"bookmarks":{"example_db-animals":{"initial_full_table_complete":true}}},"type":"STATE"}Replication methods and state fileIn the above example, we invokedtap-mssqlwithout providing astatefile
and without specifying a replication method. The three ways to replicate a given
table areFULL_TABLE,LOG_BASED, andINCREMENTAL.Full TableFull-table replication extracts all data from the source table each time the tap
is invoked.Log BasedLog_Based replication extracts change data from the MS SQL Server Change Data Capture (CDC) tables you have enrolled.This method allows you to replicate just the changes to a table e.g. the Inserts, Deletes, and Updates. For this method to work you
must enrol the database in question and tables that you wish to replicate.See :https://docs.microsoft.com/en-us/sql/relational-databases/track-changes/enable-and-disable-change-data-capture-sql-serverfor
more details.Please Note: CDC is different to Change Tracking which is a older approach for tracking change. Log Based only works with CDC, it does
not work with Change Tracking!To find out more about setting up CDC, refer to this pageMSSQL CDC SetupIncrementalIncremental replication works in conjunction with a state file to only extract
new records each time the tap is invoked. This requires a replication key to be
specified in the table's metadata as well.ExampleLet's sync theanimalstable again, but this time using incremental
replication. The replication method and replication key are set in the
table's metadata entry in properties file:{"streams":[{"tap_stream_id":"example_db-animals","table_name":"animals","schema":{...},"metadata":[{"breadcrumb":[],"metadata":{"row-count":3,"table-key-properties":["id"],"database-name":"example_db","selected-by-default":false,"is-view":false,"replication-method":"INCREMENTAL","replication-key":"id"}},...],"stream":"animals"}]}We have no meaningful state so far, so just invoke the tap in sync mode again
without a state file:$tap-mssql-cconfig.json--propertiesproperties.jsonThe output messages look very similar to when the table was replicated using the
defaultFULL_TABLEreplication method. One important difference is that theSTATEmessages now contain areplication_key_value-- a bookmark or
high-water mark -- for data that was extracted:{"type":"STATE","value":{"currently_syncing":"example_db-animals"}}{"stream":"animals","type":"SCHEMA","schema":{"type":"object","properties":{"id":{"type":["null","integer"],"minimum":-2147483648,"maximum":2147483647,"inclusion":"automatic"},"name":{"type":["null","string"],"inclusion":"available","maxLength":255},"likes_getting_petted":{"type":["null","boolean"],"inclusion":"available"}}},"key_properties":["id"]}{"stream":"animals","type":"ACTIVATE_VERSION","version":1509135204169}{"stream":"animals","type":"RECORD","version":1509135204169,"record":{"id":1,"name":"aardvark","likes_getting_petted":false}}{"stream":"animals","type":"RECORD","version":1509135204169,"record":{"id":2,"name":"bear","likes_getting_petted":false}}{"stream":"animals","type":"RECORD","version":1509135204169,"record":{"id":3,"name":"cow","likes_getting_petted":true}}{"type":"STATE","value":{"bookmarks":{"example_db-animals":{"version":1509135204169,"replication_key_value":3,"replication_key":"id"}},"currently_syncing":"example_db-animals"}}{"type":"STATE","value":{"bookmarks":{"example_db-animals":{"version":1509135204169,"replication_key_value":3,"replication_key":"id"}},"currently_syncing":null}}Note that the finalSTATEmessage has areplication_key_valueof3,
reflecting that the extraction ended on a record that had anidof3.
Subsequent invocations of the tap will pick up from this bookmark.Normally, the target will echo the lastSTATEafter it's finished processing
data. For this example, let's manually write astate.jsonfile using theSTATEmessage:{"bookmarks":{"example_db-animals":{"version":1509135204169,"replication_key_value":3,"replication_key":"id"}},"currently_syncing":null}Let's add some more animals to our farm:mssql> insert into animals (name, likes_getting_petted) values ('dog', true), ('elephant', true), ('frog', false);$tap-mssql-cconfig.json--propertiesproperties.json--statestate.jsonThis invocation extracts any data since (and including) thereplication_key_value:{"type":"STATE","value":{"bookmarks":{"example_db-animals":{"replication_key":"id","version":1509135204169,"replication_key_value":3}},"currently_syncing":"example_db-animals"}}{"key_properties":["id"],"schema":{"properties":{"name":{"maxLength":255,"inclusion":"available","type":["null","string"]},"id":{"maximum":2147483647,"minimum":-2147483648,"inclusion":"automatic","type":["null","integer"]},"likes_getting_petted":{"inclusion":"available","type":["null","boolean"]}},"type":"object"},"type":"SCHEMA","stream":"animals"}{"type":"ACTIVATE_VERSION","version":1509135204169,"stream":"animals"}{"record":{"name":"cow","id":3,"likes_getting_petted":true},"type":"RECORD","version":1509135204169,"stream":"animals"}{"record":{"name":"dog","id":4,"likes_getting_petted":true},"type":"RECORD","version":1509135204169,"stream":"animals"}{"record":{"name":"elephant","id":5,"likes_getting_petted":true},"type":"RECORD","version":1509135204169,"stream":"animals"}{"record":{"name":"frog","id":6,"likes_getting_petted":false},"type":"RECORD","version":1509135204169,"stream":"animals"}{"type":"STATE","value":{"bookmarks":{"example_db-animals":{"replication_key":"id","version":1509135204169,"replication_key_value":6}},"currently_syncing":"example_db-animals"}}{"type":"STATE","value":{"bookmarks":{"example_db-animals":{"replication_key":"id","version":1509135204169,"replication_key_value":6}},"currently_syncing":null}}Based on Stitch documentationData TypesThe json output by this tap should be JSON schema compliant and also conform to the Singer Framework standard.Noted: Below is some examples of the data transformation to present data in a standard manner for Singer Targets.A special note fordatetime2anddatetimeoffsetsMS SQL Server datatypes.Fordatetime2, it as a naïve datetime timestamp with no concept of an offset,datetime2supports nanoseconds with up to seven decimal places. Withdatetimeoffsetdatatypes, the data is normalized to UTC i.e. taking the offset as it is in MSSQL Server and converting it to a UTC so it is agnostic to the target platform - anything with a datetimeoffset can be cast into local time in the target.To work-around issues with the PYMSSQL driver, the conversion takes place on the SQL Server source to ensure there is no loss of precision leading to errors as a result of rounding.SQL DataTypeExample ValueMinMaxJSON FormatJSON TypeExample Resulttinyint2540255integer254smallint-32768-3276832767integer-32768int-2147483648-21474836482147483647integer-2147483648bigint-9223372036854775808-92233720368547758089223372036854775807integer-9223372036854775808datetime29999-12-31 23:59:59.9999999date-timestring9999-12-31 23:59:59.9999999datetimeoffset2023-08-22 08:24:32.1277000 +10:00date-timestring2023-08-21T22:24:32.1277000ZBuild InstructionsThis section dives into basic commands to buildtap-mssqlif an alteration is made to the code.To build the tapRun the following command each time you need to rebuild the tap.python3-mvenvvenv.venv/bin/activatepipinstall--upgradepippipinstall.Debugging in Visual Studio CodeTo run theinit.py python program in debug mode, you need to do the following two steps. Note: This was run within a Docker Container in Visual Studio Code.Create a .vscode/launch.json file. Note: The parameters config.json and properties.json should point to the files you have generated in previous steps above.
If you want to test state, include the state parameter as shown below and prepare an appropriate state file as per the instructions in an earlier section.{"version":"0.2.0","configurations":[{"name":"Python: Program","type":"python","request":"launch","program":"${workspaceRoot}/tap_mssql/__init__.py","args":["-c","config.json","--properties","properties.json""--state","state.json"]}]}Add a main entry to theinit.py file to run interactivelyAdd the following lines to the end of theinit.py in the tap_mssql directory.if__name__=='__main__':main()# pylint: disable=no-value-for-parameter