Author: slebresne
Date: Mon Mar 10 17:03:32 2014
New Revision: 1576002
URL: http://svn.apache.org/r1576002
Log:
Update CQL doc
Modified:
cassandra/site/publish/doc/cql3/CQL-1.2.html
cassandra/site/publish/doc/cql3/CQL-2.0.html
Modified: cassandra/site/publish/doc/cql3/CQL-1.2.html
URL:
http://svn.apache.org/viewvc/cassandra/site/publish/doc/cql3/CQL-1.2.html?rev=1576002&r1=1576001&r2=1576002&view=diff
==============================================================================
--- cassandra/site/publish/doc/cql3/CQL-1.2.html (original)
+++ cassandra/site/publish/doc/cql3/CQL-1.2.html Mon Mar 10 17:03:32 2014
@@ -59,9 +59,6 @@ CREATE KEYSPACE Excalibur
<column-definition> ::= <identifier> <type> ( PRIMARY KEY )?
| PRIMARY KEY '(' <partition-key> ( ','
<identifier> )* ')'
-<partition-key> ::= <partition-key>
- | '(' <partition-key> ( ',' <identifier> )* ')'
-
<partition-key> ::= <identifier>
| '(' <identifier> (',' <identifier> )* ')'
@@ -93,7 +90,7 @@ CREATE TABLE timeline (
other text,
PRIMARY KEY (k)
)
-</pre></pre><p>Moreover, a table must define at least one column that is not
part of the PRIMARY KEY as a row exists in Cassandra only if it contains at
least one value for one such column.</p><h4
id="createTablepartitionClustering">Partition key and clustering
columns</h4><p>In CQL, the order in which columns are defined for the
<code>PRIMARY KEY</code> matters. The first column of the key is called the
<i>partition key</i>. It has the property that all the rows sharing the same
partition key (even across table in fact) are stored on the same physical node.
Also, insertion/update/deletion on rows sharing the same partition key for a
given table are performed <i>atomically</i> and in <i>isolation</i>. Note that
it is possible to have a composite partition key, i.e. a partition key formed
of multiple columns, using an extra set of parentheses to define which columns
forms the partition key.</p><p>The remaining columns of the <code>PRIMARY
KEY</code> definition, if any, are called __c
lustering columns. On a given physical node, rows for a given partition key
are stored in the order induced by the clustering columns, making the retrieval
of rows in that clustering order particularly efficient (see <a
href="#selectStmt"><tt>SELECT</tt></a>).</p><h4
id="createTableOptions"><code><option></code></h4><p>The <code>CREATE
TABLE</code> statement supports a number of options that controls the
configuration of a new table. These options can be specified after the
<code>WITH</code> keyword.</p><p>The first of these option is <code>COMPACT
STORAGE</code>. This option is mainly targeted towards backward compatibility
for definitions created before CQL3 (see <a
href="http://www.datastax.com/dev/blog/thrift-to-cql3";>www.datastax.com/dev/blog/thrift-to-cql3</a>
for more details). The option also provides a slightly more compact layout of
data on disk but at the price of diminished flexibility and extensibility for
the table. Most notably, <code>COMPACT STORAGE</code> table
s cannot have collections and a <code>COMPACT STORAGE</code> table with at
least one clustering column supports exactly one (as in not 0 nor more than 1)
column not part of the <code>PRIMARY KEY</code> definition (which imply in
particular that you cannot add nor remove columns after creation). For those
reasons, <code>COMPACT STORAGE</code> is not recommended outside of the
backward compatibility reason evoked above.</p><p>Another option is
<code>CLUSTERING ORDER</code>. It allows to define the ordering of rows on
disk. It takes the list of the clustering column names with, for each of them,
the on-disk order (Ascending or descending). Note that this option affects <a
href="#selectOrderBy">what <code>ORDER BY</code> are allowed during
<code>SELECT</code></a>.</p><p>Table creation supports the following other
<code><property></code>:</p><table><tr><th>option
</th><th>kind </th><th>default
</th><th>description</th></tr><tr><td><code>comment</code>
</td><td><em>simple</em> </td><td>none </td><td>A free-form,
human-readable comment.</td></tr><tr><td><code>read_repair_chance</code>
</td><td><em>simple</em> </td><td>0.1 </td><td>The probability with
which to query extra nodes (e.g. more nodes than required by the consistency
level) for the purpose of read
repairs.</td></tr><tr><td><code>dclocal_read_repair_chance</code>
</td><td><em>simple</em> </td><td>0 </td><td>The probability with
which to query extra nodes (e.g. more nodes than required by the consistency
level) belonging to the same data center than the read coordinator for the
purpose of read repairs.</td></tr><tr><td><code>gc_grace_seconds</code>
</td><td><em>simple</em> </td><td>864000 </td><td>Time to wait before
garbage collecting tombstones (deletion
markers).</td></tr><tr><td><code>bloom_filter_fp_chance</code>
</td><td><em>simple</em> </td><td>0.00075 </td><td>The target probability
of false positive o
f the sstable bloom filters. Said bloom filters will be sized to provide the
provided probability (thus lowering this value impact the size of bloom filters
in-memory and on-disk)</td></tr><tr><td><code>compaction</code>
</td><td><em>map</em> </td><td><em>see below</em> </td><td>The compaction
otpions to use, see below.</td></tr><tr><td><code>compression</code>
</td><td><em>map</em> </td><td><em>see below</em> </td><td>Compression
options, see below. </td></tr><tr><td><code>replicate_on_write</code>
</td><td><em>simple</em> </td><td>true </td><td>Whether to replicate
data on write. This can only be set to false for tables with counters values.
Disabling this is dangerous and can result in random lose of counters,
don’t disable unless you are sure to know what you are
doing</td></tr><tr><td><code>caching</code>
</td><td><em>simple</em> </td><td>keys_only </td><td>Whether to cache keys
(“key cacheR
21;) and/or rows (“row cache”) for this table. Valid values are:
<code>all</code>, <code>keys_only</code>, <code>rows_only</code> and
<code>none</code>. </td></tr></table><h4
id="compactionOptions"><code>compaction</code> options</h4><p>The
<code>compaction</code> property must at least define the <code>'class'</code>
sub-option, that defines the compaction strategy class to use. The default
supported class are <code>'SizeTieredCompactionStrategy'</code> and
<code>'LeveledCompactionStrategy'</code>. Custom strategy can be provided by
specifying the full class name as a <a href="#constants">string constant</a>.
The rest of the sub-options depends on the chosen class. The sub-options
supported by the default classes are:</p><table><tr><th>option
</th><th>supported compaction strategy </th><th>default
</th><th>description </th></tr><tr><td><code>tombstone_threshold</code>
</td><td><em>all</em> </td><td>0.2 </t
d><td>A ratio such that if a sstable has more than this ratio of gcable
tombstones over all contained columns, the sstable will be compacted (with no
other sstables) for the purpose of purging those tombstones.
</td></tr><tr><td><code>tombstone_compaction_interval</code>
</td><td><em>all</em> </td><td>1 day </td><td>The
mininum time to wait after an sstable creation time before considering it for
“tombstone compaction”, where “tombstone compaction” is
the compaction triggered if the sstable has more gcable tombstones than
<code>tombstone_threshold</code>.
</td></tr><tr><td><code>min_sstable_size</code>
</td><td>SizeTieredCompactionStrategy </td><td>50MB </td><td>The size
tiered strategy groups SSTables to compact in buckets. A bucket groups SSTables
that differs from less than 50% in size. However, for small sizes, this would
result in a bucketing that is too fine grained. <code>min_sstable_size</code>
defin
es a size threshold (in bytes) below which all SSTables belong to one unique
bucket</td></tr><tr><td><code>min_threshold</code>
</td><td>SizeTieredCompactionStrategy </td><td>4 </td><td>Minimum
number of SSTables needed to start a minor
compaction.</td></tr><tr><td><code>max_threshold</code>
</td><td>SizeTieredCompactionStrategy </td><td>32 </td><td>Maximum
number of SSTables processed by one minor
compaction.</td></tr><tr><td><code>bucket_low</code>
</td><td>SizeTieredCompactionStrategy </td><td>0.5 </td><td>Size
tiered consider sstables to be within the same bucket if their size is within
[average_size * <code>bucket_low</code>, average_size *
<code>bucket_high</code> ] (i.e the default groups sstable whose sizes diverges
by at most 50%)</td></tr><tr><td><code>bucket_high</code>
</td><td>SizeTieredCompactionStrategy </td><td>1.5 </td><td>Size
tiered consider sstables to be w
ithin the same bucket if their size is within [average_size *
<code>bucket_low</code>, average_size * <code>bucket_high</code> ] (i.e the
default groups sstable whose sizes diverges by at most
50%).</td></tr><tr><td><code>sstable_size_in_mb</code>
</td><td>LeveledCompactionStrategy </td><td>5MB </td><td>The target
size (in MB) for sstables in the leveled strategy. Note that while sstable
sizes should stay less or equal to <code>sstable_size_in_mb</code>, it is
possible to exceptionally have a larger sstable as during compaction, data for
a given partition key are never split into 2 sstables</td></tr></table><p>For
the <code>compression</code> property, the following default sub-options are
available:</p><table><tr><th>option </th><th>default
</th><th>description </th></tr><tr><td><code>sstable_compression</code>
</td><td>SnappyCompressor </td><td>The compression algorithm to use. Default
compressor are: SnappyCompressor and DeflateCompresso
r. Use an empty string (<code>''</code>) to disable compression. Custom
compressor can be provided by specifying the full class name as a <a
href="#constants">string
constant</a>.</td></tr><tr><td><code>chunk_length_kb</code> </td><td>64KB
</td><td>On disk SSTables are compressed by block (to allow random
reads). This defines the size (in KB) of said block. Bigger values may improve
the compression rate, but increases the minimum size of data to be read from
disk for a read </td></tr><tr><td><code>crc_check_chance</code> </td><td>1.0
</td><td>When compression is enabled, each compressed block
includes a checksum of that block for the purpose of detecting disk bitrot and
avoiding the propagation of corruption to other replica. This option defines
the probability with which those checksums are checked during read. By default
they are always checked. Set to 0 to disable checksum checking and to 0.5 for
instance to check them every other read</td></tr></t
able><h4 id="Otherconsiderations">Other considerations:</h4><ul><li>When <a
href="#insertStmt/"updating":#updateStmt">inserting</a> a given row,
not all columns needs to be defined (except for those part of the key), and
missing columns occupy no space on disk. Furthermore, adding new columns (see
<a href=#alterStmt><tt>ALTER TABLE</tt></a>) is a constant time operation.
There is thus no need to try to anticipate future usage (or to cry when you
haven’t) when creating a table.</li></ul><h3 id="alterTableStmt">ALTER
TABLE</h3><p><i>Syntax:</i></p><pre class="syntax"><pre><alter-table-stmt>
::= ALTER (TABLE | COLUMNFAMILY) <tablename> <instruction>
+</pre></pre><h4 id="createTablepartitionClustering">Partition key and
clustering columns</h4><p>In CQL, the order in which columns are defined for
the <code>PRIMARY KEY</code> matters. The first column of the key is called the
<i>partition key</i>. It has the property that all the rows sharing the same
partition key (even across table in fact) are stored on the same physical node.
Also, insertion/update/deletion on rows sharing the same partition key for a
given table are performed <i>atomically</i> and in <i>isolation</i>. Note that
it is possible to have a composite partition key, i.e. a partition key formed
of multiple columns, using an extra set of parentheses to define which columns
forms the partition key.</p><p>The remaining columns of the <code>PRIMARY
KEY</code> definition, if any, are called __clustering columns. On a given
physical node, rows for a given partition key are stored in the order induced
by the clustering columns, making the retrieval of rows in that clusterin
g order particularly efficient (see <a
href="#selectStmt"><tt>SELECT</tt></a>).</p><h4
id="createTableOptions"><code><option></code></h4><p>The <code>CREATE
TABLE</code> statement supports a number of options that controls the
configuration of a new table. These options can be specified after the
<code>WITH</code> keyword.</p><p>The first of these option is <code>COMPACT
STORAGE</code>. This option is mainly targeted towards backward compatibility
for definitions created before CQL3 (see <a
href="http://www.datastax.com/dev/blog/thrift-to-cql3";>www.datastax.com/dev/blog/thrift-to-cql3</a>
for more details). The option also provides a slightly more compact layout of
data on disk but at the price of diminished flexibility and extensibility for
the table. Most notably, <code>COMPACT STORAGE</code> tables cannot have
collections and a <code>COMPACT STORAGE</code> table with at least one
clustering column supports exactly one (as in not 0 nor more than 1) column not
part of the <cod
e>PRIMARY KEY</code> definition (which imply in particular that you cannot add
nor remove columns after creation). For those reasons, <code>COMPACT
STORAGE</code> is not recommended outside of the backward compatibility reason
evoked above.</p><p>Another option is <code>CLUSTERING ORDER</code>. It allows
to define the ordering of rows on disk. It takes the list of the clustering
column names with, for each of them, the on-disk order (Ascending or
descending). Note that this option affects <a href="#selectOrderBy">what
<code>ORDER BY</code> are allowed during <code>SELECT</code></a>.</p><p>Table
creation supports the following other
<code><property></code>:</p><table><tr><th>option
</th><th>kind </th><th>default
</th><th>description</th></tr><tr><td><code>comment</code>
</td><td><em>simple</em> </td><td>none </td><td>A free-form,
human-readable comment.</td></tr><tr><td><code>read_repair_chance</code>
</td><td><em>simple</em
> </td><td>0.1 </td><td>The probability with which to query extra
> nodes (e.g. more nodes than required by the consistency level) for the
> purpose of read
> repairs.</td></tr><tr><td><code>dclocal_read_repair_chance</code>
> </td><td><em>simple</em> </td><td>0 </td><td>The probability with
> which to query extra nodes (e.g. more nodes than required by the consistency
> level) belonging to the same data center than the read coordinator for the
> purpose of read repairs.</td></tr><tr><td><code>gc_grace_seconds</code>
> </td><td><em>simple</em> </td><td>864000 </td><td>Time to wait
> before garbage collecting tombstones (deletion
> markers).</td></tr><tr><td><code>bloom_filter_fp_chance</code>
> </td><td><em>simple</em> </td><td>0.00075 </td><td>The target
> probability of false positive of the sstable bloom filters. Said bloom
> filters will be sized to provide the provided probability (thus lowering
> this value impact the size of bloom filters in-memory and on-disk)</
td></tr><tr><td><code>compaction</code> </td><td><em>map</em>
</td><td><em>see below</em> </td><td>The compaction otpions to use, see
below.</td></tr><tr><td><code>compression</code>
</td><td><em>map</em> </td><td><em>see below</em> </td><td>Compression
options, see below. </td></tr><tr><td><code>replicate_on_write</code>
</td><td><em>simple</em> </td><td>true </td><td>Whether to replicate
data on write. This can only be set to false for tables with counters values.
Disabling this is dangerous and can result in random lose of counters,
don’t disable unless you are sure to know what you are
doing</td></tr><tr><td><code>caching</code>
</td><td><em>simple</em> </td><td>keys_only </td><td>Whether to cache keys
(“key cache”) and/or rows (“row cache”) for this table.
Valid values are: <code>all</code>, <code>keys_only</code>,
<code>rows_only</code> and <code>none</code>. </td></tr></tabl
e><h4 id="compactionOptions"><code>compaction</code> options</h4><p>The
<code>compaction</code> property must at least define the <code>'class'</code>
sub-option, that defines the compaction strategy class to use. The default
supported class are <code>'SizeTieredCompactionStrategy'</code> and
<code>'LeveledCompactionStrategy'</code>. Custom strategy can be provided by
specifying the full class name as a <a href="#constants">string constant</a>.
The rest of the sub-options depends on the chosen class. The sub-options
supported by the default classes are:</p><table><tr><th>option
</th><th>supported compaction strategy </th><th>default
</th><th>description </th></tr><tr><td><code>tombstone_threshold</code>
</td><td><em>all</em> </td><td>0.2 </td><td>A
ratio such that if a sstable has more than this ratio of gcable tombstones over
all contained columns, the sstable will be compacted (with no other sstables)
for the purpose
of purging those tombstones.
</td></tr><tr><td><code>tombstone_compaction_interval</code>
</td><td><em>all</em> </td><td>1 day </td><td>The
mininum time to wait after an sstable creation time before considering it for
“tombstone compaction”, where “tombstone compaction” is
the compaction triggered if the sstable has more gcable tombstones than
<code>tombstone_threshold</code>.
</td></tr><tr><td><code>min_sstable_size</code>
</td><td>SizeTieredCompactionStrategy </td><td>50MB </td><td>The size
tiered strategy groups SSTables to compact in buckets. A bucket groups SSTables
that differs from less than 50% in size. However, for small sizes, this would
result in a bucketing that is too fine grained. <code>min_sstable_size</code>
defines a size threshold (in bytes) below which all SSTables belong to one
unique bucket</td></tr><tr><td><code>min_threshold</code>
</td><td>SizeTieredCompactionStrategy
</td><td>4 </td><td>Minimum number of SSTables needed to start a
minor compaction.</td></tr><tr><td><code>max_threshold</code>
</td><td>SizeTieredCompactionStrategy </td><td>32 </td><td>Maximum
number of SSTables processed by one minor
compaction.</td></tr><tr><td><code>bucket_low</code>
</td><td>SizeTieredCompactionStrategy </td><td>0.5 </td><td>Size
tiered consider sstables to be within the same bucket if their size is within
[average_size * <code>bucket_low</code>, average_size *
<code>bucket_high</code> ] (i.e the default groups sstable whose sizes diverges
by at most 50%)</td></tr><tr><td><code>bucket_high</code>
</td><td>SizeTieredCompactionStrategy </td><td>1.5 </td><td>Size
tiered consider sstables to be within the same bucket if their size is within
[average_size * <code>bucket_low</code>, average_size *
<code>bucket_high</code> ] (i.e the default groups sstable whose sizes diverges
by at most 50%).</td></tr><tr><td><code>sstable_size_in_mb</code>
</td><td>LeveledCompactionStrategy </td><td>5MB </td><td>The target
size (in MB) for sstables in the leveled strategy. Note that while sstable
sizes should stay less or equal to <code>sstable_size_in_mb</code>, it is
possible to exceptionally have a larger sstable as during compaction, data for
a given partition key are never split into 2 sstables</td></tr></table><p>For
the <code>compression</code> property, the following default sub-options are
available:</p><table><tr><th>option </th><th>default
</th><th>description </th></tr><tr><td><code>sstable_compression</code>
</td><td>SnappyCompressor </td><td>The compression algorithm to use. Default
compressor are: SnappyCompressor and DeflateCompressor. Use an empty string
(<code>''</code>) to disable compression. Custom compressor can be provided by
specifying the full class name as a <a href="#constants">string constant</a>.</
td></tr><tr><td><code>chunk_length_kb</code> </td><td>64KB
</td><td>On disk SSTables are compressed by block (to allow random reads). This
defines the size (in KB) of said block. Bigger values may improve the
compression rate, but increases the minimum size of data to be read from disk
for a read </td></tr><tr><td><code>crc_check_chance</code> </td><td>1.0
</td><td>When compression is enabled, each compressed block includes a
checksum of that block for the purpose of detecting disk bitrot and avoiding
the propagation of corruption to other replica. This option defines the
probability with which those checksums are checked during read. By default they
are always checked. Set to 0 to disable checksum checking and to 0.5 for
instance to check them every other read</td></tr></table><h4
id="Otherconsiderations">Other considerations:</h4><ul><li>When <a
href="#insertStmt/"updating":#updateStmt">inserting</a> a given row,
not all columns needs to b
e defined (except for those part of the key), and missing columns occupy no
space on disk. Furthermore, adding new columns (see <a
href=#alterStmt><tt>ALTER TABLE</tt></a>) is a constant time operation. There
is thus no need to try to anticipate future usage (or to cry when you
haven’t) when creating a table.</li></ul><h3 id="alterTableStmt">ALTER
TABLE</h3><p><i>Syntax:</i></p><pre class="syntax"><pre><alter-table-stmt>
::= ALTER (TABLE | COLUMNFAMILY) <tablename> <instruction>
<instruction> ::= ALTER <identifier> TYPE <type>
| ADD <identifier> <type>
@@ -131,7 +128,7 @@ CREATE CUSTOM INDEX ON users (email) USI
</pre></pre><p><br/><i>Sample:</i></p><pre class="sample"><pre>INSERT INTO
NerdMovies (movie, director, main_actor, year)
VALUES ('Serenity', 'Joss Whedon', 'Nathan Fillion', 2005)
USING TTL 86400;
-</pre></pre><p>The <code>INSERT</code> statement writes one or more columns
for a given row in a table. Note that since a row is identified by its
<code>PRIMARY KEY</code>, the columns that compose it must be specified. Also,
since a row only exists when it contains one value for a column not part of the
<code>PRIMARY KEY</code>, one such value must be specified too.</p><p>Note that
unlike in SQL, <code>INSERT</code> does not check the prior existence of the
row: the row is created if none existed before, and updated otherwise.
Furthermore, there is no mean to know which of creation or update happened. In
fact, the semantic of <code>INSERT</code> and <code>UPDATE</code> are
identical.</p><p>All updates for an <code>INSERT</code> are applied atomically
and in isolation.</p><p>Please refer to the <a
href="#updateOptions"><code>UPDATE</code></a> section for information on the
<code><option></code> available and to the <a
href="#collections">collections</a> section for use of <code>&
lt;collection-literal></code>. Also note that <code>INSERT</code> does not
support counters, while <code>UPDATE</code> does.</p><h3
id="updateStmt">UPDATE</h3><p><i>Syntax:</i></p><pre
class="syntax"><pre><update-stmt> ::= UPDATE <tablename>
+</pre></pre><p>The <code>INSERT</code> statement writes one or more columns
for a given row in a table. Note that since a row is identified by its
<code>PRIMARY KEY</code>, at least the columns composing it must be
specified.</p><p>Note that unlike in SQL, <code>INSERT</code> does not check
the prior existence of the row: the row is created if none existed before, and
updated otherwise. Furthermore, there is no mean to know which of creation or
update happened. In fact, the semantic of <code>INSERT</code> and
<code>UPDATE</code> are identical.</p><p>All updates for an <code>INSERT</code>
are applied atomically and in isolation.</p><p>Please refer to the <a
href="#updateOptions"><code>UPDATE</code></a> section for information on the
<code><option></code> available and to the <a
href="#collections">collections</a> section for use of
<code><collection-literal></code>. Also note that <code>INSERT</code> does
not support counters, while <code>UPDATE</code> does.</p><h3 id="updateSt
mt">UPDATE</h3><p><i>Syntax:</i></p><pre class="syntax"><pre><update-stmt>
::= UPDATE <tablename>
( USING <option> ( AND <option> )* )?
SET <assignment> ( ',' <assignment> )*
WHERE <where-clause>
@@ -155,7 +152,7 @@ SET director = 'Joss Whedon',
WHERE movie = 'Serenity';
UPDATE UserActions SET total = total + 2 WHERE user =
B70DE1D0-9908-4AE3-BE34-5573E5B09F14 AND action = 'click';
-</pre></pre><p><br/>The <code>UPDATE</code> statement writes one or more
columns for a given row in a table. The <code><where-clause></code> is used
to select the row to update and must include all columns composing the
<code>PRIMARY KEY</code> (the <code>IN</code> relation is only supported for
the last column of the partition key). Other columns values are specified
through <code><assignment></code> after the <code>SET</code>
keyword.</p><p>Note that unlike in SQL, <code>UPDATE</code> does not check the
prior existence of the row: the row is created if none existed before, and
updated otherwise. Furthermore, there is no mean to know which of creation or
update happened. In fact, the semantic of <code>INSERT</code> and
<code>UPDATE</code> are identical.</p><p>In an <code>UPDATE</code> statement,
all updates within the same partition key are applied atomically and in
isolation.</p><p>The <code>c = c + 3</code> form of
<code><assignment></code> is used to increment/decrement
counters. The identifier after the ‘=’ sign <strong>must</strong>
be the same than the one before the ‘=’ sign (Only
increment/decrement is supported on counters, not the assignment of a specific
value).</p><p>The <code>id = id + <collection-literal></code> and
<code>id[value1] = value2</code> forms of <code><assignment></code> are for
collections. Please refer to the <a href="#collections">relevant section</a>
for more details.</p><h4
id="updateOptions"><code><options></code></h4><p>The <code>UPDATE</code> and
<code>INSERT</code> statements allows to specify the following options for the
insertion:</p><ul><li><code>TIMESTAMP</code>: sets the timestamp for the
operation. If not specified, the current time of the insertion (in
microseconds) is used. This is usually a suitable
default.</li><li><code>TTL</code>: allows to specify an optional Time To Live
(in seconds) for the inserted values. If set, the inserted values are
automatically removed from th
e database after the specified time. Note that the TTL concerns the inserted
values, not the column themselves. This means that any subsequent update of the
column will also reset the TTL (to whatever TTL is specified in that update).
By default, values never expire.</li></ul><h3
id="deleteStmt">DELETE</h3><p><i>Syntax:</i></p><pre
class="syntax"><pre><delete-stmt> ::= DELETE ( <selection> ( ','
<selection> )* )?
+</pre></pre><p><br/>The <code>UPDATE</code> statement writes one or more
columns for a given row in a table. The <code><where-clause></code> is used
to select the row to update and must include all columns composing the
<code>PRIMARY KEY</code> (the <code>IN</code> relation is only supported for
the last column of the partition key). Other columns values are specified
through <code><assignment></code> after the <code>SET</code>
keyword.</p><p>Note that unlike in SQL, <code>UPDATE</code> does not check the
prior existence of the row: the row is created if none existed before, and
updated otherwise. Furthermore, there is no mean to know which of creation or
update happened. In fact, the semantic of <code>INSERT</code> and
<code>UPDATE</code> are identical.</p><p>In an <code>UPDATE</code> statement,
all updates within the same partition key are applied atomically and in
isolation.</p><p>The <code>c = c + 3</code> form of
<code><assignment></code> is used to increment/decrement
counters. The identifier after the ‘=’ sign <strong>must</strong>
be the same than the one before the ‘=’ sign (Only
increment/decrement is supported on counters, not the assignment of a specific
value).</p><p>The <code>id = id + <collection-literal></code> and
<code>id[value1] = value2</code> forms of <code><assignment></code> are for
collections. Please refer to the <a href="#collections">relevant section</a>
for more details.</p><h4
id="updateOptions"><code><options></code></h4><p>The <code>UPDATE</code> and
<code>INSERT</code> statements allows to specify the following options for the
insertion:</p><ul><li><code>TIMESTAMP</code>: sets the timestamp for the
operation. If not specified, the current time of the insertion (in
microseconds) is used. This is usually a suitable
default.</li><li><code>TTL</code>: allows to specify an optional Time To Live
(in seconds) for the inserted values. If set, the inserted values are
automatically removed from th
e database after the specified time. Note that the TTL concerns the inserted
values, not the column themselves. This means that any subsequent update of the
column will also reset the TTL (to whatever TTL is specified in that update).
By default, values never expire. A TTL of 0 or a negative one is equivalent to
no TTL.</li></ul><h3 id="deleteStmt">DELETE</h3><p><i>Syntax:</i></p><pre
class="syntax"><pre><delete-stmt> ::= DELETE ( <selection> ( ','
<selection> )* )?
FROM <tablename>
( USING TIMESTAMP <integer>)?
WHERE <where-clause>
Modified: cassandra/site/publish/doc/cql3/CQL-2.0.html
URL:
http://svn.apache.org/viewvc/cassandra/site/publish/doc/cql3/CQL-2.0.html?rev=1576002&r1=1576001&r2=1576002&view=diff
==============================================================================
--- cassandra/site/publish/doc/cql3/CQL-2.0.html (original)
+++ cassandra/site/publish/doc/cql3/CQL-2.0.html Mon Mar 10 17:03:32 2014
@@ -60,9 +60,6 @@ CREATE KEYSPACE Excalibur
<column-definition> ::= <identifier> <type> ( STATIC )? ( PRIMARY KEY
)?
| PRIMARY KEY '(' <partition-key> ( ','
<identifier> )* ')'
-<partition-key> ::= <partition-key>
- | '(' <partition-key> ( ',' <identifier> )* ')'
-
<partition-key> ::= <identifier>
| '(' <identifier> (',' <identifier> )* ')'
