Read

Jump to the Code block for a combined complete example.

Setup

The following examples will use the setup and record below to illustrate single record data retreival from an Aerospike database.

import aerospike

# Define host configuration
config = {
    'hosts': [ ('127.0.0.1', 3000) ]
}
# Establishes a connection to the server
client = aerospike.client(config).connect()

# Creates a key with the namespace "sandbox", set "ufodata", and user key 5001
key = ('sandbox', 'ufodata', 5001)

The record structure:

+------+----------+----------+----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+
| PK   | occurred | reported | posted   | report                                                                                                                                                                                                                 | location                                                   |
+------+----------+----------+----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+
| 5001 | 20220531 | 20220601 | 20220601 | MAP('{"shape":["circle", "flash", "disc"], "summary":"Large flying disc flashed in the sky above the student union. Craziest thing I've ever seen!", "city":"Ann Arbor", "state":"Michigan", "duration":"5 minutes"}') | GeoJSON('{"type":"Point","coordinates":[42.2808,83.743]}') |
+------+----------+----------+----------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+------------------------------------------------------------+

Policies

Instead of using the default read policies, we can set them on a per command basis.

The following example creates a new read policy and sets the socket timeout for the command.

# Create new read policy
policy = {'socket_timeout': 300}

Read a record

Record exists

Checking record existence is faster than getting the record because it only needs to look at the primary index.

# Returns key and metadata if exists, None if not
(key, meta) = client.exists(key, policy=policy)

# Do something
exists = True
if meta == None:
    exists = False
print('Exists: ', exists)

# Close the connection to the server
client.close()

Record metadata only

Read record metadata (generation and expiration information) without reading the bins for a specified key.

# Get record metadata
(key, meta) = client.exists(key, policy=policy)

# Do something
print('Record: ', meta)

# Close the connection to the server
client.close()

Whole record

Read the record metadata and all bins for a specified key.

# Get whole record
(key_, meta, bins) = client.get(key, policy=policy)

# Do something
print('Record: ', bins)

# Close the connection to the server
client.close()

Specific bins

Read the record metadata and the report and location bins from the record.

# Get bins 'report' and 'location'
(key_, meta, bins) = client.select(key, ("report", "location"), policy=policy)

# Do something
print('Record: ', bins)

# Close the connection to the server
client.close()

Code block

Expand this section for a single code block to read a record

import aerospike

# Define host configuration
config = {
    'hosts': [ ('127.0.0.1', 3000) ]
}
# Establishes a connection to the server
client = aerospike.client(config).connect()

# Creates a key with the namespace "sandbox", set "ufodata", and user key 5001
key = ('sandbox', 'ufodata', 5001)

# Create new read policy
policy = {'socket_timeout': 300}

# Get whole record
(key_, meta, bins) = client.get(key, policy=policy)

# Do something
print('Record: ', bins)

# Close the connection to the server
client.close()