ayradb 0.4.5b0

AyraDB python client

Python AyraDB client library

This module provides a simple interface to perform actions on an AyraDB installation.

Initialization

The AyraDB class is the main interface to an AyraDB installation.
In order to instantiate an AyraDB object, a valid host must be provided.

from ayradb import AyraDB

db: AyraDB = AyraDB(ip="192.168.0.1")

All possible operations a user can perform are described below.

Create a table

AyraDB allows users to create three different types of tables:

• FIXED_LENGTH,
• PADDED,
• NOSQL

Convenient APIs to create tables of each type are available.

Fixed lenght tables

For fixed_length tables, maximum key column size, maximum table size, and at least one field must be provided. New fields can be added later.

from ayradb import Table, Column

table = db.table("new_fixed_length_table")
fields = [{Column.NAME: "field0", Column.MAX_LENGTH: 1024},
           {Column.NAME: "field1", Column.MAX_LENGTH: 1024},
           {Column.NAME: "field2", Column.MAX_LENGTH: 1024}]

max_key_column_size_byte = 1024
rct = table.create(Table.TYPE_FIXED_LENGTH, columns=fields, key_max_size=max_key_column_size_byte).wait_response()
if rct.success is True:
    print("New fixed length table created!")
else:
    print(f"Error code: {rct.error_code}")

Padded

For padded tables, at least one field must be provided, and new fields can be added later.

from ayradb import Table, Column

table = db.table("new_padded_table")
fields = [{Column.NAME: "field0"},
            {Column.NAME: "field1"},
            {Column.NAME: "field2"}]
max_key_column_size_byte = 1024
rct = table.create(Table.TYPE_PADDED, columns=fields, key_max_size=max_key_column_size_byte).wait_response()
if rct.success is True:
    print("New padded table created!")
else:
    print(f"Error code: {rct.error_code}")

Nosql

Nosql tables do not have a fixed structure, so the fields argument is omitted.

from ayradb import Table, Column

table = db.table("new_nosql_table")
rct = table.create(Table.TYPE_NOSQL).wait_response()
if rct.success is True:
    print("New nosql table created!")
else:
    print(f"Error code: {rct.error_code}")

Insert a record

If the new record is not already contained in table, then it is inserted, otherwise it is updated.

table = db.table("new_fixed_length_table")
key_value = 'key_column'
fields = {
            "field0": b'value0',
            "field1": b'value1',
            "field2": b'value2',
         }
ri = table.upsert_record(key_value, fields).wait_response()
if ri.success is True:
    print("New record inserted!")
else:
    print(f"Error code: {ri.error_code}")

The fields argument must be specified, and the field value argument must be in the form of a byte Array.

Read a record

Read can be limited to a subset of fields with the fields argument.

table = db.table("new_fixed_length_table")
key_value = "key_column"
field_names = ["field0", "field2"]
rr = table.read_record(key_value, fields=field_names).wait_response()
if rr.success is True:
    for key, value in rr.content.items():
        print("Field name: " + key)
        print("Field value: " + value.decode())
else:
    print(f"Error code: {rr.error_code}")

If the fields argument is set to null, all fields are retrieved.

table = db.table("new_fixed_length_table")
key_value = "key_column"
rr = table.read_record(key_value, fields=[]).wait_response()
if rr.success is True:
    for key, value in rr.content.items():
        print("Field name: " + key)
        print("Field value: " + value.decode())
else:
    print(f"Error code: {rr.error_code}")

Delete a record

table = db.table("new_fixed_length_table")
key_value = "key_column"
rd = table.delete_record(key_value).wait_response()
if rd.success is True: 
      print("Record successfully deleted!")
else:
    print(f"Error code: {rd.error_code}")

Deletion in Nosql tables can be limited to a subset of fields with the fields argument.

table = db.table("new_nosql_table")
key_value = "key_column_ns"
field_names = ["field0ns", "field1ns"]
rd = table.delete_record(key_value, fields=field_names).wait_response()
if rd.success is True:
    print("Record fields successfully deleted!")
else:
    print(f"Error code: {rd.error_code}")

The operation completes even if a record with the provided key does not exist in the table.

Retrieve table structure

Retrieve table structure retrieves the structures of the record of a table.

table = db.table("new_fixed_length_table")
rts = table.get_structure().wait_response()
if rts.success is True:
    for i in range(len(rts.structure)):
        field = rts.structure[i]
        print(f"Position: {i}, Field name: {field.get('column_label')}, Field max length: {int(field.get('column_max_net_length',-1))} bytes")
else:
    print(f"Error code: {rts.error_code}")

Truncate a table

Truncate table deletes all the records of an existing table, leaving the structure of the table intact and usable.

table = db.table("new_fixed_length_table")
rt = table.truncate().wait_response()
if rt.success is True:
    print("Table is now empty!")
else:
    print(f"Error code: {rt.error_code}")

Delete a table

Delete table destroys an existing table.

table = db.table("new_fixed_length_table")
rd = table.drop().wait_response()
if rd.success is True:
    print("Table destroyed!")
else:
    print(f"Error code: {rd.error_code}")

Scan a table

A convenient API is provided to allow table scans.
Each table is composed of a certain number of segments: in order to perform a scan, the number of segments of the table must be retrieved. Each segment must be scanned independently.

Each time a record is retrieved, AyraDB returns a last_hash value, used to retrieve the next record in the segment.

When the end of a segment is reached, the success parameter becomes false and we can scan the next segment. Verify that the returned error matches ScanError.SEGMENT_END

Scan can be limited to a subset of fields with the fields argument.

from ayradb import ScanError

table = db.table("new_fixed_length_table")
rsi = table.scan_init().wait_response()
if rsi.success is True:
    number_of_segments = rsi.segments
    field_names = ["field0", "field1"]

    for segment in range(0, number_of_segments-1):
        rs = table.scan(segment= segment, fields=field_names).wait_response()
        while rs.success is True:
            # DO SOMETHING WITH CURRENT RECORD
            rs = table.scan(segment, last_hash=rs.last_hash).wait_response()
        if rs.error_code != ScanError.SEGMENT_END:
            print(f"Error code: {rs.error_code}")
else:
    print(f"Error code: {rsi.error_code}")

SQL queries

AyraDB provides an API to perform SQL-like queries on a single table. AyraDB SQL queries can contain the following clauses:

• WHERE
• GROUP_BY
• HAVING
• ORDER_BY
• LIMIT
• DISTINCT

IMPORTANT: the semicolon (';') at the end of the query is mandatory.

query = db.new_raw_query('SELECT * FROM %s WHERE field="condition";', % table_name)
stream = query.execute().stream
while not stream.is_closed():
   responses = stream.take_when_available()
       for response in responses:
           for record in response.content:
               # Store or use the record    

Connection handling

When all operations are completed, it's best practice to close the connection with the following command.

db.close_connection()

Error handling

When an action fails, a response object is returned to the user. Success will return false in case of a failure.
The response object contains an error code.

A list of all possible errors, divided by action, is provided below.

Error 100: Internal error

Create a table

Error -1: Field max lenght required
Error -2: Key max lenght required
Error -3: Not enough nodes provided
Error 1: Table already exists

Insert a record

Error -1: Invalid field name
Error 1: Table not found
Error 2: Field not found
Error 3: Field too long

Read a record

Error -1: Invalid field name
Error 1: Table not found
Error 2: Record not found

Delete a record

Error -1: Invalid field name
Error 1: Table not found
Error 2: Field not found

Retrieve table structure

Error -1: Invalid field name
Error 1: Table not found

Truncate a table

Error 1: Table not found

Delete a table

Error -1: Invalid field name
Error 1: Table not found

Scan a table

Error -1: Invalid field name
Error 1: Table not found
Error 2: End of segment