This repository is no longer maintained. The initial goal was to have a place for fixes and updates to the pyhdb project, which did not accept pull requests and has not been very active lately. However, we currently lack the time to maintain this repository. In case you have any questions, please contact the github user Bouncner.
This repository is a fork of the official repository at https://github.com/SAP/PyHDB. The goal of this repo was to have it maintained by the open-source community.
A pure Python client for the SAP HANA Database based on the SAP HANA Database SQL Command Network Protocol.
pyhdb supports Python 2.7, 3.3, 3.4, 3.5 and also PyPy on Linux, OSX and Windows. It implements a large part of the DBAPI Specification v2.0 (PEP 249). We plan to support Python 2.6 again in the future.
- Install
- Getting started
- Establish a database connection
- Cursor object
- Large Objects (LOBs)
- Stored Procedures
- Transaction handling
- Contribute
Install from GitHub via pip:
$ pip install git+https://github.com/hpi-epic/pyhana.git
You can also install the latest version direct from a cloned git repository.
$ git clone https://github.com/hpi-epic/pyhana.git
$ cd pyhdb
$ python setup.py install
If you do not have access to a SAP HANA server, go to the SAP HANA Developer Center and choose one of the options to get your own trial SAP HANA Server.
For using PyHDB with hanatrial instance, follow this guide.
The basic pyhdb usage is common to database adapters implementing the DBAPI 2.0 interface (PEP 249). The following example shows how easy it's to use the pyhdb module.
>>> import pyhdb
>>> connection = pyhdb.connect(
host="example.com",
port=30015,
user="user",
password="secret"
)
>>> cursor = connection.cursor()
>>> cursor.execute("SELECT 'Hello Python World' FROM DUMMY")
>>> cursor.fetchone()
(u"Hello Python World",)
>>> connection.close()
The function pyhdb.connect
creates a new database session and returns a new Connection
instance.
Please note that port isn't the instance number of you SAP HANA database. The SQL port of your SAP
HANA is made up of 3<instance-number>15
for example the port of the default instance number 00
is 30015
.
Currently pyhdb only supports the user and password authentication method. If you need another authentication method like SAML or Kerberos than please open a GitHub issue. Also there is currently no support of encrypted network communication between client and database.
With the method cursor
of your Connection
object you create a new Cursor
object.
This object is able to execute SQL statements and fetch one or multiple rows of the resultset from the database.
>>> cursor = connection.cursor()
>>> cursor.execute("SELECT SCHEMA_NAME, TABLE_NAME FROM TABLES")
After you executed a statement you can fetch one or multiple rows from the resultset.
>>> cursor.fetchone()
(u'SYS', u'DUMMY')
>>> cursor.fetchmany(3)
[(u'SYS', u'DUMMY'), (u'SYS', u'PROCEDURE_DATAFLOWS'), (u'SYS', u'PROCEDURE_MAPPING')]
You can also fetch all rows from your resultset.
>>> cursor.fetchall()
[(u'SYS', u'DUMMY'), (u'SYS', u'PROCEDURE_DATAFLOWS'), (u'SYS', u'PROCEDURE_MAPPING'), ...]
With the execute method you can also execute DDL statements like CREATE TABLE
.
>>> cursor.execute('CREATE TABLE PYHDB_TEST("NAMES" VARCHAR (255) null)')
>>> connection.commit() # necessary to commit the changes
You can also execute DML Statements with the execute method like INSERT
or DELETE
. The Cursor
attribute rowcount
contains the number of affected rows by the last statement.
>>> cursor.execute("INSERT INTO PYHDB_TEST VALUES('Hello Python World')")
>>> cursor.rowcount
1
>>> connection.commit() # necessary to commit the changes
Three different types of LOBs are supported and corresponding LOB classes have been implemented: * Blob - binary LOB data * Clob - string LOB data containing only ascii characters * NClob - string (unicode for Python 2.x) LOB data containing any valid unicode character
LOB instance provide a file-like interface (similar to StringIO instances) for accessing LOB data. For HANA LOBs lazy loading of the actual data is implemented behind the scenes. An initial select statement for a LOB only loads the first 1024 bytes on the client:
>>> mylob = cursor.execute('select myclob from mytable where id=:1', [some_id]).fetchone()[0] >>> mylob <Clob length: 2000 (currently loaded from hana: 1024)>
By calling the read(<num-chars>)-method more data will be loaded from the database once <num-chars> exceeds the number of currently loaded data:
>>> myload.read(1500) # -> returns the first 1500 chars, by loading extra 476 chars from the db >>> mylob <Clob length: 2000 (currently loaded from hana: 1500)> >>> myload.read() # -> returns the last 500 chars by loading them from the db >>> mylob <Clob length: 2000 (currently loaded from hana: 2000)>
Using the seek()
methods it is possible to point the file pointer position within the LOB to arbitrary positions.
tell()
will return the current position.
LOBs can be written to the database via insert
or update
-statemens with LOB data provided either
as strings or LOB instances:
>>> from pyhdb import NClob >>> nclob_data = u'朱の子ましける日におえつかうまつ' >>> nclob = NClob(nclob_data) >>> cursor.execute('update mynclob set nclob_1=:1, nclob_2=:2 where id=:3', [nclob, nclob_data, myid])
Note
Currently LOBs can only be written in the database for sizes up to 128k (entire amount of data provided in one
update
or insert
statement). This constraint will be removed in one of the next releases of PyHDB.
This limitation does however not apply when reading LOB data from the database.
Rudimentary support for Stored Procedures call, scalar parameters only:
The script shall call the stored procedure PROC_ADD2 (source below):
>>> sql_to_prepare = 'call PROC_ADD2 (?, ?, ?, ?)' >>> params = {'A':2, 'B':5, 'C':None, 'D': None} >>> psid = cursor.prepare(sql_to_prepare) >>> ps = cursor.get_prepared_statement(psid) >>> cursor.execute_prepared(ps, [params]) >>> result = cursor.fetchall() >>> for l in result: >>> print l
from the stored procedure:
create procedure PROC_ADD2 (in a int, in b int, out c int, out d char) language sqlscript reads sql data as begin c := :a + :b; d := 'A'; end
Please note that all cursors created from the same connection are not isolated. Any change done by one cursor is immediately visible to all other cursors from same connection. Cursors created from different connections are isolated as the connection based on the normal transaction handling.
The connection objects provides to method commit
which commit any pending transaction of the
connection. The method rollback
undo all changes since the last commit.
If you found bugs or have other issues than you are welcome to create a GitHub Issue. If you have questions about usage or something similar please create a Stack Overflow Question with tag pyhdb.
pyhdb provides a test suite which covers the most use-cases and protocol parts. To run the test suite
you need the pytest
and mock
package. Afterwards just run py.test
inside of the root
directory of the repository.
$ pip install pytest mock
$ py.test
You can also test different python version with tox
.
$ pip install tox
$ tox
For debugging purposes it is sometimes useful to get detailed tracing information about packages sent to hana and those received from the database. There are two ways to turn on the print out of tracing information:
- Set the environment variable HDB_TRACING=1 before starting Python, e.g. (bash-syntax!):
$ HDB_TRACE=1 python
- Import the pyhdb module and set
pyhdb.tracing = True
Then perform some statements on the database and enjoy the output.
To get tracing information when running pytest provide the -s
option:
$ HDB_TRACE=1 py.test -s
- Allow execution of stored database procedure
- Support of
SELECT FOR UPDATE
- Authentication methods
- SAML
- Kerberos