add CQL TTL support

patch by pyaskevich; reviewed by jbellis for CASSANDRA-2476

git-svn-id: https://svn.apache.org/repos/asf/cassandra/branches/cassandra-0.8.1@1101234 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Jonathan Ellis 2011-05-09 21:40:27 +00:00
parent 0427c832b0
commit fcd02e3a66
10 changed files with 252 additions and 59 deletions

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@ -1,12 +1,15 @@
1.0-dev 1.0-dev
0.8.1
* add support for insert, delete in cql BATCH (CASSANDRA-2537) * add support for insert, delete in cql BATCH (CASSANDRA-2537)
* add support for IN to cql SELECT, UPDATE (CASSANDRA-2553) * add support for IN to cql SELECT, UPDATE (CASSANDRA-2553)
* add timestamp support to cql INSERT, UPDATE, and BATCH (CASSANDRA-2555) * add timestamp support to cql INSERT, UPDATE, and BATCH (CASSANDRA-2555)
0.8.1
* add support for comparator parameters and a generic ReverseType * add support for comparator parameters and a generic ReverseType
(CASSANDRA-2355) (CASSANDRA-2355)
* add CompositeType and DynamicCompositeType (CASSANDRA-2231) * add CompositeType and DynamicCompositeType (CASSANDRA-2231)
* add CQL TTL support (CASSANDRA-2476)
0.8.0-? 0.8.0-?
* faster flushes and compaction from fixing excessively pessimistic * faster flushes and compaction from fixing excessively pessimistic

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@ -74,7 +74,7 @@ h2. INSERT
_Synopsis:_ _Synopsis:_
bc. bc.
INSERT INTO <COLUMN FAMILY> (KEY, <col>, <col>, ...) VALUES (<key>, <val>, <val>, ...) [USING CONSISTENCY <LEVEL> [AND TIMESTAMP <timestamp>]]; INSERT INTO <COLUMN FAMILY> (KEY, <col>, <col>, ...) VALUES (<key>, <val>, <val>, ...) [USING CONSISTENCY <LEVEL> [AND TIMESTAMP <timestamp>] [AND TTL <timeToLive>]];
An @INSERT@ is used to write one or more columns to a record in a Cassandra column family. No results are returned. An @INSERT@ is used to write one or more columns to a record in a Cassandra column family. No results are returned.
@ -85,7 +85,7 @@ h2. UPDATE
_Synopsis:_ _Synopsis:_
bc. bc.
UPDATE <COLUMN FAMILY> [USING <CONSISTENCY> [AND TIMESTAMP <timestamp>]] UPDATE <COLUMN FAMILY> [USING <CONSISTENCY> [AND TIMESTAMP <timestamp>] [AND TTL <timeToLive>]]
SET name1 = value1, name2 = value2 WHERE KEY = keyname; SET name1 = value1, name2 = value2 WHERE KEY = keyname;
An @UPDATE@ is used to write one or more columns to a record in a Cassandra column family. No results are returned. An @UPDATE@ is used to write one or more columns to a record in a Cassandra column family. No results are returned.
@ -111,6 +111,13 @@ UPDATE ... [USING TIMESTAMP <timestamp>] ...
@UPDATE@ supports setting client-supplied optional timestamp for modification. @UPDATE@ supports setting client-supplied optional timestamp for modification.
h3. TTL
bc.
UPDATE ... [USING TTL <timeToLive>] ...
@UPDATE@ supports setting time to live (TTL) for each of the columns in @UPDATE@ statement.
h3. Specifying Columns and Row h3. Specifying Columns and Row
bc. bc.

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@ -33,17 +33,19 @@ public abstract class AbstractModification
protected final String columnFamily; protected final String columnFamily;
protected final ConsistencyLevel cLevel; protected final ConsistencyLevel cLevel;
protected final Long timestamp; protected final Long timestamp;
protected final int timeToLive;
public AbstractModification(String columnFamily, ConsistencyLevel cLevel) public AbstractModification(String columnFamily, Attributes attrs)
{ {
this(columnFamily, cLevel, null); this(columnFamily, attrs.getConsistencyLevel(), attrs.getTimestamp(), attrs.getTimeToLive());
} }
public AbstractModification(String columnFamily, ConsistencyLevel cLevel, Long timestamp) public AbstractModification(String columnFamily, ConsistencyLevel cLevel, Long timestamp, int timeToLive)
{ {
this.columnFamily = columnFamily; this.columnFamily = columnFamily;
this.cLevel = cLevel; this.cLevel = cLevel;
this.timestamp = timestamp; this.timestamp = timestamp;
this.timeToLive = timeToLive;
} }
public String getColumnFamily() public String getColumnFamily()
@ -76,6 +78,11 @@ public abstract class AbstractModification
return timestamp != null; return timestamp != null;
} }
public int getTimeToLive()
{
return timeToLive;
}
/** /**
* Convert statement into a list of mutations to apply on the server * Convert statement into a list of mutations to apply on the server
* *

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@ -0,0 +1,79 @@
/*
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*
*/
package org.apache.cassandra.cql;
import org.apache.cassandra.thrift.ConsistencyLevel;
/**
* Class to contain attributes for statements
*/
public class Attributes
{
private ConsistencyLevel cLevel;
private Long timestamp;
private int timeToLive;
public Attributes()
{}
public Attributes(ConsistencyLevel cLevel, Long timestamp, int timeToLive)
{
this.cLevel = cLevel;
this.timestamp = timestamp;
this.timeToLive = timeToLive;
}
public ConsistencyLevel getConsistencyLevel()
{
return cLevel;
}
public void setConsistencyLevel(ConsistencyLevel cLevel)
{
this.cLevel = cLevel;
}
public Long getTimestamp()
{
return timestamp;
}
public void setTimestamp(Long timestamp)
{
this.timestamp = timestamp;
}
public int getTimeToLive()
{
return timeToLive;
}
public void setTimeToLive(int timeToLive)
{
this.timeToLive = timeToLive;
}
public String toString()
{
return String.format("Attributes(consistency=%s, timestamp=%s, timeToLive=%s)", cLevel, timestamp, timeToLive);
}
}

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@ -43,18 +43,22 @@ public class BatchStatement
// global timestamp to apply for each mutation // global timestamp to apply for each mutation
protected final Long timestamp; protected final Long timestamp;
// global time to live
protected final int timeToLive;
/** /**
* Creates a new BatchStatement from a list of statements and a * Creates a new BatchStatement from a list of statements and a
* Thrift consistency level. * Thrift consistency level.
* *
* @param statements a list of UpdateStatements * @param statements a list of UpdateStatements
* @param level Thrift consistency level enum * @param attrs additional attributes for statement (CL, timestamp, timeToLive)
*/ */
public BatchStatement(List<AbstractModification> statements, ConsistencyLevel level, Long timestamp) public BatchStatement(List<AbstractModification> statements, Attributes attrs)
{ {
this.statements = statements; this.statements = statements;
consistency = level; this.consistency = attrs.getConsistencyLevel();
this.timestamp = timestamp; this.timestamp = attrs.getTimestamp();
this.timeToLive = attrs.getTimeToLive();
} }
public List<AbstractModification> getStatements() public List<AbstractModification> getStatements()
@ -67,6 +71,11 @@ public class BatchStatement
return consistency; return consistency;
} }
public int getTimeToLive()
{
return timeToLive;
}
public List<RowMutation> getMutations(String keyspace, ClientState clientState) throws InvalidRequestException public List<RowMutation> getMutations(String keyspace, ClientState clientState) throws InvalidRequestException
{ {
List<RowMutation> batch = new LinkedList<RowMutation>(); List<RowMutation> batch = new LinkedList<RowMutation>();

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@ -201,9 +201,7 @@ whereClause returns [WhereClause clause]
*/ */
insertStatement returns [UpdateStatement expr] insertStatement returns [UpdateStatement expr]
: { : {
Long timestamp = null; Attributes attrs = new Attributes();
ConsistencyLevel cLevel = null;
Map<Term, Term> columns = new HashMap<Term, Term>(); Map<Term, Term> columns = new HashMap<Term, Term>();
List<Term> columnNames = new ArrayList<Term>(); List<Term> columnNames = new ArrayList<Term>();
@ -213,19 +211,20 @@ insertStatement returns [UpdateStatement expr]
'(' K_KEY ( ',' column_name=term { columnNames.add($column_name.item); } )+ ')' '(' K_KEY ( ',' column_name=term { columnNames.add($column_name.item); } )+ ')'
K_VALUES K_VALUES
'(' key=term ( ',' column_value=term { columnValues.add($column_value.item); })+ ')' '(' key=term ( ',' column_value=term { columnValues.add($column_value.item); })+ ')'
( usingClause[cLevel, timestamp] )? ( usingClause[attrs] )?
{ {
return new UpdateStatement($columnFamily.text, cLevel, columnNames, columnValues, Collections.singletonList(key), timestamp); return new UpdateStatement($columnFamily.text, columnNames, columnValues, Collections.singletonList(key), attrs);
} }
; ;
usingClause[ConsistencyLevel cLevel, Long timestamp] usingClause[Attributes attrs]
: K_USING usingClauseObjective[cLevel, timestamp] ( K_AND? usingClauseObjective[cLevel, timestamp] )? : K_USING usingClauseObjective[attrs] ( K_AND? usingClauseObjective[attrs] )*
; ;
usingClauseObjective[ConsistencyLevel cLevel, Long timestamp] usingClauseObjective[Attributes attrs]
: K_CONSISTENCY K_LEVEL { cLevel = ConsistencyLevel.valueOf($K_LEVEL.text); } : K_CONSISTENCY K_LEVEL { attrs.setConsistencyLevel(ConsistencyLevel.valueOf($K_LEVEL.text)); }
| K_TIMESTAMP ts=INTEGER { timestamp = Long.valueOf($ts.text); } | K_TIMESTAMP ts=INTEGER { attrs.setTimestamp(Long.valueOf($ts.text)); }
| K_TTL t=INTEGER { attrs.setTimeToLive(Integer.parseInt($t.text)); }
; ;
/** /**
@ -254,15 +253,16 @@ usingClauseObjective[ConsistencyLevel cLevel, Long timestamp]
*/ */
batchStatement returns [BatchStatement expr] batchStatement returns [BatchStatement expr]
: { : {
Long timestamp = null; Attributes attrs = new Attributes();
ConsistencyLevel cLevel = ConsistencyLevel.ONE; attrs.setConsistencyLevel(ConsistencyLevel.ONE);
List<AbstractModification> statements = new ArrayList<AbstractModification>(); List<AbstractModification> statements = new ArrayList<AbstractModification>();
} }
K_BEGIN K_BATCH ( usingClause[cLevel, timestamp] )? K_BEGIN K_BATCH ( usingClause[attrs] )?
s1=batchStatementObjective ';'? { statements.add(s1); } ( sN=batchStatementObjective ';'? { statements.add(sN); } )* s1=batchStatementObjective ';'? { statements.add(s1); } ( sN=batchStatementObjective ';'? { statements.add(sN); } )*
K_APPLY K_BATCH endStmnt K_APPLY K_BATCH endStmnt
{ {
return new BatchStatement(statements, cLevel, timestamp); return new BatchStatement(statements, attrs);
} }
; ;
@ -287,19 +287,18 @@ batchStatementObjective returns [AbstractModification statement]
*/ */
updateStatement returns [UpdateStatement expr] updateStatement returns [UpdateStatement expr]
: { : {
Long timestamp = null; Attributes attrs = new Attributes();
ConsistencyLevel cLevel = null;
Map<Term, Term> columns = new HashMap<Term, Term>(); Map<Term, Term> columns = new HashMap<Term, Term>();
List<Term> keyList = null; List<Term> keyList = null;
} }
K_UPDATE columnFamily=( IDENT | STRING_LITERAL | INTEGER ) K_UPDATE columnFamily=( IDENT | STRING_LITERAL | INTEGER )
( usingClause[cLevel, timestamp] )? ( usingClause[attrs] )?
K_SET termPair[columns] (',' termPair[columns])* K_SET termPair[columns] (',' termPair[columns])*
K_WHERE ( K_KEY '=' key=term { keyList = Collections.singletonList(key); } K_WHERE ( K_KEY '=' key=term { keyList = Collections.singletonList(key); }
| |
K_KEY K_IN '(' keys=termList { keyList = $keys.items; } ')' ) K_KEY K_IN '(' keys=termList { keyList = $keys.items; } ')' )
{ {
return new UpdateStatement($columnFamily.text, cLevel, columns, keyList, timestamp); return new UpdateStatement($columnFamily.text, columns, keyList, attrs);
} }
; ;
@ -321,7 +320,8 @@ deleteStatement returns [DeleteStatement expr]
} }
K_DELETE K_DELETE
( cols=termList { columnsList = $cols.items; })? ( cols=termList { columnsList = $cols.items; })?
K_FROM columnFamily=( IDENT | STRING_LITERAL | INTEGER ) ( K_USING K_CONSISTENCY K_LEVEL )? K_FROM columnFamily=( IDENT | STRING_LITERAL | INTEGER )
( K_USING K_CONSISTENCY K_LEVEL { cLevel = ConsistencyLevel.valueOf($K_LEVEL.text); } )?
K_WHERE ( K_KEY '=' key=term { keyList = Collections.singletonList(key); } K_WHERE ( K_KEY '=' key=term { keyList = Collections.singletonList(key); }
| K_KEY K_IN '(' keys=termList { keyList = $keys.items; } ')' | K_KEY K_IN '(' keys=termList { keyList = $keys.items; } ')'
)? )?
@ -466,6 +466,7 @@ K_PRIMARY: P R I M A R Y;
K_INTO: I N T O; K_INTO: I N T O;
K_VALUES: V A L U E S; K_VALUES: V A L U E S;
K_TIMESTAMP: T I M E S T A M P; K_TIMESTAMP: T I M E S T A M P;
K_TTL: T T L;
// Case-insensitive alpha characters // Case-insensitive alpha characters
fragment A: ('a'|'A'); fragment A: ('a'|'A');

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@ -48,7 +48,7 @@ public class DeleteStatement extends AbstractModification
public DeleteStatement(List<Term> columns, String columnFamily, ConsistencyLevel cLevel, List<Term> keys) public DeleteStatement(List<Term> columns, String columnFamily, ConsistencyLevel cLevel, List<Term> keys)
{ {
super(columnFamily, cLevel, null); super(columnFamily, cLevel, null, 0);
this.columns = columns; this.columns = columns;
this.keys = keys; this.keys = keys;

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@ -559,6 +559,9 @@ public class QueryProcessor
case BATCH: case BATCH:
BatchStatement batch = (BatchStatement) statement.statement; BatchStatement batch = (BatchStatement) statement.statement;
if (batch.getTimeToLive() != 0)
throw new InvalidRequestException("Global TTL on the BATCH statement is not supported.");
for (AbstractModification up : batch.getStatements()) for (AbstractModification up : batch.getStatements())
{ {
if (up.isSetConsistencyLevel()) if (up.isSetConsistencyLevel())

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@ -53,32 +53,20 @@ public class UpdateStatement extends AbstractModification
* level, and key term. * level, and key term.
* *
* @param columnFamily column family name * @param columnFamily column family name
* @param cLevel the thrift consistency level
* @param columns a map of column name/values pairs * @param columns a map of column name/values pairs
* @param keys the keys to update * @param keys the keys to update
* @param timestamp timestamp to use for mutation, if set to null then System.currentTimeMillis() * @param attrs additional attributes for statement (CL, timestamp, timeToLive)
*/ */
public UpdateStatement(String columnFamily, ConsistencyLevel cLevel, Map<Term, Term> columns, List<Term> keys, Long timestamp) public UpdateStatement(String columnFamily,
Map<Term, Term> columns,
List<Term> keys,
Attributes attrs)
{ {
super(columnFamily, cLevel, timestamp); super(columnFamily, attrs);
this.columns = columns; this.columns = columns;
this.keys = keys; this.keys = keys;
} }
/**
* Creates a new UpdateStatement from a column family name, columns map,
* and key term.
*
* @param columnFamily column family name
* @param columns a map of column name/values pairs
* @param keys the keys to update
* @param timestamp timestamp to use for mutation, if set to null then System.currentTimeMillis()
*/
public UpdateStatement(String columnFamily, Map<Term, Term> columns, List<Term> keys, Long timestamp)
{
this(columnFamily, null, columns, keys, timestamp);
}
/** /**
* Creates a new UpdateStatement from a column family name, a consistency level, * Creates a new UpdateStatement from a column family name, a consistency level,
@ -86,20 +74,18 @@ public class UpdateStatement extends AbstractModification
* alternate update format, <code>INSERT</code>. * alternate update format, <code>INSERT</code>.
* *
* @param columnFamily column family name * @param columnFamily column family name
* @param cLevel the thrift consistency level
* @param columnNames list of column names * @param columnNames list of column names
* @param columnValues list of column values (corresponds to names) * @param columnValues list of column values (corresponds to names)
* @param keys the keys to update * @param keys the keys to update
* @param timestamp timestamp to use for mutation, if set to null then System.currentTimeMillis() * @param attrs additional attributes for statement (CL, timestamp, timeToLive)
*/ */
public UpdateStatement(String columnFamily, public UpdateStatement(String columnFamily,
ConsistencyLevel cLevel,
List<Term> columnNames, List<Term> columnNames,
List<Term> columnValues, List<Term> columnValues,
List<Term> keys, List<Term> keys,
Long timestamp) Attributes attrs)
{ {
super(columnFamily, cLevel, timestamp); super(columnFamily, attrs);
this.columnNames = columnNames; this.columnNames = columnNames;
this.columnValues = columnValues; this.columnValues = columnValues;
@ -184,7 +170,8 @@ public class UpdateStatement extends AbstractModification
validateColumn(metadata, colName, colValue); validateColumn(metadata, colName, colValue);
rm.add(new QueryPath(columnFamily, null, colName), rm.add(new QueryPath(columnFamily, null, colName),
colValue, colValue,
(timestamp == null) ? getTimestamp() : timestamp); (timestamp == null) ? getTimestamp() : timestamp,
getTimeToLive());
} }
return rm; return rm;
@ -224,11 +211,13 @@ public class UpdateStatement extends AbstractModification
public String toString() public String toString()
{ {
return String.format("UpdateStatement(columnFamily=%s, keys=%s, columns=%s, consistency=%s)", return String.format("UpdateStatement(columnFamily=%s, keys=%s, columns=%s, consistency=%s, timestamp=%s, timeToLive=%s)",
columnFamily, columnFamily,
keys, keys,
columns, columns,
cLevel); getConsistencyLevel(),
timestamp,
timeToLive);
} }
public AbstractType<?> getKeyType(String keyspace) public AbstractType<?> getKeyType(String keyspace)

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@ -807,6 +807,15 @@ class TestCql(ThriftTester):
APPLY BATCH APPLY BATCH
""") """)
# BATCH should not allow setting global TTL
assert_raises(cql.ProgrammingError,
cursor.execute,
"""
BEGIN BATCH USING TTL 130374
UPDATE StandardString1 SET name = 'name here' WHERE KEY = 'TimestampedUser4'
APPLY BATCH
""")
assert_raises(cql.ProgrammingError, assert_raises(cql.ProgrammingError,
cursor.execute, cursor.execute,
""" """
@ -842,7 +851,7 @@ class TestCql(ThriftTester):
assert r[2] == "p4ssw0rd", \ assert r[2] == "p4ssw0rd", \
"unrecognized value '%s'" % r[1] "unrecognized value '%s'" % r[1]
def test_insert_with_timestamp(self): def test_insert_with_timestamp_and_ttl(self):
"insert statement should support setting timestamp" "insert statement should support setting timestamp"
cursor = init() cursor = init()
cursor.compression = 'NONE' cursor.compression = 'NONE'
@ -877,7 +886,50 @@ class TestCql(ThriftTester):
assert r[1] == "name here", \ assert r[1] == "name here", \
"unrecognized value '%s'" % r[1] "unrecognized value '%s'" % r[1]
def test_update_with_timestamp(self): # and INSERT with TTL
cursor.execute("INSERT INTO StandardString1 (KEY, name) VALUES ('TimestampedUser2', 'name here') USING TTL 5678")
# try to read it
cursor.execute("SELECT * FROM StandardString1 WHERE KEY = 'TimestampedUser2'")
assert cursor.rowcount == 1, "expected 1 results, got %d" % cursor.rowcount
colnames = [col_d[0] for col_d in cursor.description]
assert colnames[1] == "name", \
"unrecognized name '%s'" % colnames[1]
r = cursor.fetchone()
assert r[1] == "name here", \
"unrecognized value '%s'" % r[1]
# and INSERT with CONSISTENCY, TIMESTAMP and TTL together
cursor.execute("INSERT INTO StandardString1 (KEY, name) VALUES ('TimestampedUser3', 'name here') USING TTL 4587 AND TIMESTAMP 1303743619771318 AND CONSISTENCY ONE")
# try to read it
cursor.execute("SELECT * FROM StandardString1 WHERE KEY = 'TimestampedUser3'")
assert cursor.rowcount == 1, "expected 1 results, got %d" % cursor.rowcount
colnames = [col_d[0] for col_d in cursor.description]
assert colnames[1] == "name", \
"unrecognized name '%s'" % colnames[1]
r = cursor.fetchone()
assert r[1] == "name here", \
"unrecognized value '%s'" % r[1]
# and INSERT with TTL
cursor.execute("INSERT INTO StandardString1 (KEY, name) VALUES ('TimestampedUser14', 'name here') USING TTL 1 AND CONSISTENCY ONE")
# wait for column to expire
time.sleep(5)
# try to read it
cursor.execute("SELECT * FROM StandardString1 WHERE KEY = 'TimestampedUser14'")
assert cursor.rowcount == 1, "expected 1 results, got %d" % cursor.rowcount
r = cursor.fetchone()
assert len(r) == 1, "expected 0 results, got %d" % len(r)
def test_update_with_timestamp_and_ttl(self):
"update statement should support setting timestamp" "update statement should support setting timestamp"
cursor = init() cursor = init()
cursor.compression = 'NONE' cursor.compression = 'NONE'
@ -911,3 +963,46 @@ class TestCql(ThriftTester):
r = cursor.fetchone() r = cursor.fetchone()
assert r[1] == "name here", \ assert r[1] == "name here", \
"unrecognized value '%s'" % r[1] "unrecognized value '%s'" % r[1]
# UPDATE with TTL
cursor.execute("UPDATE StandardString1 USING TTL 13030 SET name = 'name here' WHERE KEY = 'TimestampedUser4'")
# try to read it
cursor.execute("SELECT * FROM StandardString1 WHERE KEY = 'TimestampedUser4'")
assert cursor.rowcount == 1, "expected 1 results, got %d" % cursor.rowcount
colnames = [col_d[0] for col_d in cursor.description]
assert colnames[1] == "name", \
"unrecognized name '%s'" % colnames[1]
r = cursor.fetchone()
assert r[1] == "name here", \
"unrecognized value '%s'" % r[1]
# UPDATE with CONSISTENCY, TIMESTAMP and TTL together
cursor.execute("UPDATE StandardString1 USING CONSISTENCY ONE AND TIMESTAMP 1303743619771318 AND TTL 13037 SET name = 'name here' WHERE KEY = 'TimestampedUser5'")
# try to read it
cursor.execute("SELECT * FROM StandardString1 WHERE KEY = 'TimestampedUser5'")
assert cursor.rowcount == 1, "expected 1 results, got %d" % cursor.rowcount
colnames = [col_d[0] for col_d in cursor.description]
assert colnames[1] == "name", \
"unrecognized name '%s'" % colnames[1]
r = cursor.fetchone()
assert r[1] == "name here", \
"unrecognized value '%s'" % r[1]
# UPDATE with TTL
cursor.execute("UPDATE StandardString1 USING CONSISTENCY ONE TTL 1 SET name = 'name here' WHERE KEY = 'TimestampedUser6'")
# wait for column to expire
time.sleep(5)
# try to read it
cursor.execute("SELECT * FROM StandardString1 WHERE KEY = 'TimestampedUser6'")
assert cursor.rowcount == 1, "expected 1 results, got %d" % cursor.rowcount
r = cursor.fetchone()
assert len(r) == 1, "expected 0 results, got %d" % len(r)