Schema Metadata

PHP Driver exposes the Cassandra Schema Metadata for keyspaces, tables, and columns.

Background

Given

a running Cassandra cluster

And

the following schema:

CREATE KEYSPACE simplex WITH replication = {
  'class': 'SimpleStrategy',
  'replication_factor': 1
} AND DURABLE_WRITES = false;
USE simplex;
CREATE TABLE values (
  id int PRIMARY KEY,
  bigint_value bigint,
  decimal_value decimal,
  double_value double,
  float_value float,
  int_value int,
  varint_value varint,
  ascii_value ascii,
  text_value text,
  varchar_value varchar,
  timestamp_value timestamp,
  blob_value blob,
  uuid_value uuid,
  timeuuid_value timeuuid,
  inet_value inet,
  list_value List<text>,
  map_value Map<timestamp, double>,
  set_value Set<float>
) WITH
    bloom_filter_fp_chance=0.5 AND
    caching='ALL' AND
    comment='Schema Metadata Feature' AND
    compaction={'class': 'LeveledCompactionStrategy', 'sstable_size_in_mb' : 37} AND
    compression={'sstable_compression': 'DeflateCompressor'} AND
    dclocal_read_repair_chance=0.25 AND
    gc_grace_seconds=3600 AND
    populate_io_cache_on_flush='true' AND
    read_repair_chance=0.75 AND
    replicate_on_write='false';

Getting keyspace metadata

Given

the following example:

<?php
$cluster  = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session  = $cluster->connect("simplex");

$schema   = $session->schema();
$keyspace = $schema->keyspace("simplex");

echo "Name: " . $keyspace->name() . "\n";
echo "Replication Class: " . $keyspace->replicationClassName() . "\n";
foreach ($keyspace->replicationOptions() as $key => $value) {
  echo "  " . $key . ":" . $value . "\n";
}
echo "Has Durable Writes: " . ($keyspace->hasDurableWrites() ? "True" : "False" ). "\n";

When

it is executed

Then

its output should contain:

Name: simplex
Replication Class: org.apache.cassandra.locator.SimpleStrategy
  replication_factor:1
Has Durable Writes: False

Getting table metadata

Given

the following example:

<?php
$cluster = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session = $cluster->connect("simplex");

$schema  = $session->schema();
$table   = $schema->keyspace("simplex")->table("values");

echo "Name: " . $table->name() . "\n";
echo "Bloom Filter: " . $table->bloomFilterFPChance() . "\n";
$patterns = array('/{/', '/"/', '/:/', '/keys/');
$table_caching = explode(",", $table->caching());
echo "Caching: " . preg_replace($patterns, "", $table_caching[0]) . "\n";
echo "Comment: " . $table->comment() . "\n";
echo "Compaction Class: " . $table->compactionStrategyClassName() . "\n";
foreach ($table->compactionStrategyOptions() as $key => $value) {
  echo "  " . $key . ":" . $value . "\n";
}
foreach ($table->compressionParameters() as $key => $value) {
  echo "  " . $key . ":" . $value . "\n";
}
echo "DC/Local Read Repair Chance: " . $table->localReadRepairChance() . "\n";
echo "Garbage Collection Grace Seconds: " . $table->gcGraceSeconds() . "\n";
echo "Read Repair Chance: " . $table->readRepairChance() . "\n";

When

it is executed

Then

its output should contain:

Name: values
Bloom Filter: 0.5
Caching: ALL
Comment: Schema Metadata Feature
Compaction Class: org.apache.cassandra.db.compaction.LeveledCompactionStrategy
  sstable_size_in_mb:37
  sstable_compression:org.apache.cassandra.io.compress.DeflateCompressor
DC/Local Read Repair Chance: 0.25
Garbage Collection Grace Seconds: 3600
Read Repair Chance: 0.75

Getting table metadata for io cache and replicate on write

Given

the following example:

<?php
$cluster = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session = $cluster->connect("simplex");

$schema  = $session->schema();
$table   = $schema->keyspace("simplex")->table("values");

echo "Populate I/O Cache on Flush: " . ($table->populateIOCacheOnFlush() ? "True" : "False") . "\n";
echo "Replicate on Write: " . ($table->replicateOnWrite() ? "True" : "False") . "\n";

When

it is executed

Then

its output should contain:

Populate I/O Cache on Flush: True
Replicate on Write: False

Getting table metadata for index interval

Given

the following example:

<?php
$cluster = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session = $cluster->connect("simplex");
$cql = "ALTER TABLE values WITH index_interval = '512'";
$session->execute(new Cassandra\SimpleStatement($cql));
$schema  = $session->schema();
$table   = $schema->keyspace("simplex")->table("values");

echo "Index Interval: " . $table->indexInterval() . "\n";

When

it is executed

Then

its output should contain:

Index Interval: 512

Getting table metadata for default TTL, memtable flush period and speculative retry

Given

the following example:

<?php
$cluster = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session = $cluster->connect("simplex");
$cql = "ALTER TABLE values WITH default_time_to_live = '10000' AND "
       . "memtable_flush_period_in_ms = '100' AND "
       . "speculative_retry = '10ms'";
$session->execute(new Cassandra\SimpleStatement($cql));
$schema  = $session->schema();
$table   = $schema->keyspace("simplex")->table("values");

echo "Default TTL: " . $table->defaultTTL() . "\n";
echo "Memtable Flush Period: " . $table->memtableFlushPeriodMs() . "\n";
echo "Speculative Retry: " . intval($table->speculativeRetry()) . "\n";

When

it is executed

Then

its output should contain:

Default TTL: 10000
Memtable Flush Period: 100
Speculative Retry: 10

Getting table metadata for max and min index intervals

Given

the following example:

<?php
$cluster = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session = $cluster->connect("simplex");
$cql = "ALTER TABLE values WITH max_index_interval = '16' AND "
       . "min_index_interval = '4'";
$session->execute(new Cassandra\SimpleStatement($cql));
$schema  = $session->schema();
$table   = $schema->keyspace("simplex")->table("values");

echo "Maximum Index Interval: " . $table->maxIndexInterval() . "\n";
echo "Minimum Index Interval: " . $table->minIndexInterval() . "\n";

When

it is executed

Then

its output should contain:

Maximum Index Interval: 16
Minimum Index Interval: 4

Getting metadata for column and types

Given

the following example:

<?php
$cluster   = Cassandra::cluster()
                   ->withContactPoints('127.0.0.1')
                   ->build();
$session   = $cluster->connect("simplex");
$schema    = $session->schema();
$table     = $schema->keyspace("simplex")->table("values");
foreach ($table->columns() as $column) {
    echo $column->name() . ': ' . $column->type() . "\n";
}

When

it is executed

Then

its output should contain these lines in any order:

ascii_value: ascii
bigint_value: bigint
blob_value: blob
decimal_value: decimal
double_value: double
float_value: float
id: int
inet_value: inet
int_value: int
list_value: list<varchar>
map_value: map<timestamp, double>
set_value: set<float>
text_value: varchar
timestamp_value: timestamp
timeuuid_value: timeuuid
uuid_value: uuid
varchar_value: varchar
varint_value: varint