blocks|key|2739770|text|有一些系统表可以提供有关存储的键空间、表、列的信息。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2739771|在cqlsh控制台中尝试运行以下命令：|2739772|获取键空间信息
SELECT+*+FROM+system.schema_keyspaces+;|ordered-list-item|offset|length|style|CODE|2739773|获取表格信息
SELECT+columnfamily_name+FROM+system.schema_columnfamilies+WHERE+keyspace_name+=+'keyspace+name';|2739774|获取表格信息
SELECT+column_name,+type,+validator+FROM+system.schema_columns+WHERE+keyspace_name+=+'keyspace+name'+AND+columnfamily_name+=+'table+name';|2739775|自V5.0.x+文档以来|2739776|获取键空间信息
SELECT+*+FROM+system_schema.keyspaces;|2739777|获取表格信息
SELECT+*+FROM+system_schema.tables+WHERE+keyspace_name+=+'keyspace+name';|2739778|获取表格信息
SELECT+*+FROM+system_schema.columns+WHERE+keyspace_name+=+'keyspace_name'+AND+table_name+=+'table_name';|2739779|自V6.0以来文档|2739780|获取键空间信息
SELECT+*+FROM+system_schema.keyspaces|2739781|获取表格信息
SELECT+*+FROM+system_schema.tables+WHERE+keyspace_name+=+'keyspace+name';|2739782|获取表格信息
SELECT+*+FROM+system_schema.columns+WHERE+keyspace_name+=+'keyspace_name'+AND+table_name+=+'table_name';|2739783|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.datastax.com/en/dse/5.1/cql/cql/cql_using/useQuerySystemTable.html|1|https://docs.datastax.com/en/dse/6.0/cql/cql/cql_using/useQuerySystemTable.html^0|0|0|8|13|0|7|2P|0|7|3U|0|8|2|0|0|8|12|0|7|21|0|7|2W|0|7|2|1|0|8|11|0|7|21|0|7|2W|0^^$0|@$1|2|3|4|5|6|7|1E|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1F|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|1G|8|@$G|1H|H|1I|I|J]]|9|@]|A|$]]|$1|K|3|L|5|F|7|1J|8|@$G|1K|H|1L|I|J]]|9|@]|A|$]]|$1|M|3|N|5|F|7|1M|8|@$G|1N|H|1O|I|J]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1P|8|@]|9|@$G|1Q|H|1R|1|1S]]|A|$]]|$1|Q|3|R|5|F|7|1T|8|@$G|1U|H|1V|I|J]]|9|@]|A|$]]|$1|S|3|T|5|F|7|1W|8|@$G|1X|H|1Y|I|J]]|9|@]|A|$]]|$1|U|3|V|5|F|7|1Z|8|@$G|20|H|21|I|J]]|9|@]|A|$]]|$1|W|3|X|5|6|7|22|8|@]|9|@$G|23|H|24|1|25]]|A|$]]|$1|Y|3|Z|5|F|7|26|8|@$G|27|H|28|I|J]]|9|@]|A|$]]|$1|10|3|11|5|F|7|29|8|@$G|2A|H|2B|I|J]]|9|@]|A|$]]|$1|12|3|13|5|F|7|2C|8|@$G|2D|H|2E|I|J]]|9|@]|A|$]]|$1|14|3|-4|5|6|7|2F|8|@]|9|@]|A|$]]]|15|$16|$5|17|18|19|A|$1A|1B]]|1C|$5|17|18|19|A|$1A|1D]]]]

There are system tables which can provide information about stored keyspaces, tables, columns.
Try run follows commands in cqlsh console:
<ol>
<li>Get keyspaces info
<code>SELECT * FROM system.schema_keyspaces ;</code>
</li>
<li>Get tables info
<code>SELECT columnfamily_name FROM system.schema_columnfamilies WHERE keyspace_name = 'keyspace name';</code>
</li>
<li>Get table info
<code>SELECT column_name, type, validator FROM system.schema_columns WHERE keyspace_name = 'keyspace name' AND columnfamily_name = 'table name';</code>
</li>
</ol>
Since v 5.0.x
<a href="https://docs.datastax.com/en/dse/5.1/cql/cql/cql_using/useQuerySystemTable.html" rel="noreferrer">Docs</a>
<ol>
<li>Get keyspaces info
<code>SELECT * FROM system_schema.keyspaces;</code>
</li>
<li>Get tables info
<code>SELECT * FROM system_schema.tables WHERE keyspace_name = 'keyspace name';</code>
</li>
<li>Get table info
<code>SELECT * FROM system_schema.columns
WHERE keyspace_name = 'keyspace_name' AND table_name = 'table_name';</code>
</li>
</ol>
Since v 6.0
<a href="https://docs.datastax.com/en/dse/6.0/cql/cql/cql_using/useQuerySystemTable.html" rel="noreferrer">Docs</a>
<ol>
<li>Get keyspaces info
<code>SELECT * FROM system_schema.keyspaces</code>
</li>
<li>Get tables info
<code>SELECT * FROM system_schema.tables WHERE keyspace_name = 'keyspace name';</code>
</li>
<li>Get table info
<code>SELECT * FROM system_schema.columns
WHERE keyspace_name = 'keyspace_name' AND table_name = 'table_name';</code>
</li>
</ol>

blocks|key|1988229|text|从cqlsh执行describe+tables;|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1988230|entityMap^0|1|5|8|G|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

From <code>cqlsh</code> execute <code>describe tables;</code>

blocks|key|1395628|text|desc+keyspaces;++//+list+all+databases/collections+names
use+anyKeyspace;++//+select+any+database
desc+tables;++++++//+list+all+tables+in+collection/+database|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1395629|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>desc keyspaces; // list all databases/collections names
use anyKeyspace; // select any database
desc tables; // list all tables in collection/ database

</code></pre>

blocks|key|1988188|text|您可以使用datastax核心驱动程序和群集元数据实现您想要的结果。下面是一个示例，它将列出键空间中的所有表和每个表中的列：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1988189|+Cluster+cluster=+Cluster.builder().addContactPoint(clusterIp).build();
++++Metadata+metadata+=cluster.getMetadata();

+++Collection<TableMetadata>+tablesMetadata=+metadata.getKeyspace("mykeyspacename").getTables();
++++for(TableMetadata+tm:tablesMetadata){
++++++++System.out.println("Table+name:"%2Btm.getName());
++++++++Collection<ColumnMetadata>+columnsMetadata=tm.getColumns();++++++++++++
++++++++for(ColumnMetadata+cm:columnsMetadata){
++++++++++++String+columnName=cm.getName();
++++++++++++System.out.println("Column+name:"%2BcolumnName);
++++++++}
++++}|code-block|syntax|javascript|1988190|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can achieve what you want using datastax core driver and cluster metadata. Here is an example which will list all the tables in your keyspace and columns in each table:

<pre><code> Cluster cluster= Cluster.builder().addContactPoint(clusterIp).build();
 Metadata metadata =cluster.getMetadata();

 Collection&lt;TableMetadata&gt; tablesMetadata= metadata.getKeyspace("mykeyspacename").getTables();
 for(TableMetadata tm:tablesMetadata){
 System.out.println("Table name:"+tm.getName());
 Collection&lt;ColumnMetadata&gt; columnsMetadata=tm.getColumns(); 
 for(ColumnMetadata cm:columnsMetadata){
 String columnName=cm.getName();
 System.out.println("Column name:"+columnName);
 }
 }
</code></pre>

blocks|key|1988265|text|为了DSE。如果稍后发布，请检查system_schema密钥空间。从…|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1988266|cqlsh+>+desc+keyspaces;

spark_system++system_schema++"OpsCenter"++cfs_archive+++++++++"HiveMetaStore"
system_auth++++cfs++++++++++demobeta++++++++++++dsefs++++++++++
dse_security++hypermedia+++++dse_leases+++system_traces+++++++dse_perf+++++++
solr_admin++++system+++++++++system_distributed++dse_system|code-block|syntax|javascript|1988267|如果您看到'system_schema‘，那么表的元数据就在这个键空间中。|1988268|cqlsh>use+system_schema;

cqlsh>select+keyspace_name,table_name+from+tables+where+keyspace_name+=+'system';|1988269|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

For DSE. If later release check for system_schema keyspace. 
from 

<pre><code>cqlsh &gt; desc keyspaces;

spark_system system_schema "OpsCenter" cfs_archive "HiveMetaStore"
system_auth cfs demobeta dsefs 
dse_security hypermedia dse_leases system_traces dse_perf 
solr_admin system system_distributed dse_system
</code></pre>

if you see 'system_schema' then the metadata for tables is in this keyspace. 

<pre><code>cqlsh&gt;use system_schema;

cqlsh&gt;select keyspace_name,table_name from tables where keyspace_name = 'system';
</code></pre>

blocks|key|1988283|text|若要列出所有表(仅列出表名)，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1988284|DESC+tables;|offset|length|style|CODE|1988285|若要列出所有表和架构(CQL创建语句)，|1988286|DESC+{$KEYSPACE_NAME}，而{$KEYSPACE_NAME}是键空间的名称。|1988287|我使用的是从官方网站下载的Apache+Cassandra+3.11.4二进制包：|1988288|cql>+show+version;
[cqlsh+5.0.1+%7C+Cassandra+3.11.4+%7C+CQL+spec+3.4.4+%7C+Native+protocol+v4]|code-block|syntax|javascript|1988289|Apache的CQL引用如下：https://cassandra.apache.org/doc/cql3/CQL-3.0.html|1988290|entityMap|0|LINK|mutability|MUTABLE|url|https://cassandra.apache.org/doc/cql3/CQL-3.0.html^0|0|0|C|0|0|0|L|N|G|0|0|0|F|1E|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@$D|14|E|15|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|16|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|17|8|@$D|18|E|19|F|G]|$D|1A|E|1B|F|G]]|9|@]|A|$]]|$1|L|3|M|5|6|7|1C|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1D|8|@]|9|@]|A|$Q|R]]|$1|S|3|T|5|6|7|1E|8|@]|9|@$D|1F|E|1G|1|1H]]|A|$]]|$1|U|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

To list all the tables (only the table names),

<code>DESC tables;</code>

To list all the tables and the schemas (CQL creation statements),

<code>DESC {$KEYSPACE_NAME}</code> whereas <code>{$KEYSPACE_NAME}</code> is the name of the keyspace.

I am using Apache Cassandra 3.11.4 binary package downloaded from the official site:

<pre><code>cql&gt; show version;
[cqlsh 5.0.1 | Cassandra 3.11.4 | CQL spec 3.4.4 | Native protocol v4]
</code></pre>

The Apache Cassandra's CQL reference is here: <a href="https://cassandra.apache.org/doc/cql3/CQL-3.0.html" rel="nofollow noreferrer">https://cassandra.apache.org/doc/cql3/CQL-3.0.html</a>

blocks|key|2739889|text|尝试运行以下查询：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2739890|cqlsh>+describe+keyspace+<keyspace_name>;|code-block|syntax|javascript|2739891|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

try running the following query:
<pre><code>cqlsh&gt; describe keyspace &lt;keyspace_name&gt;;
</code></pre>

blocks|key|1988308|text|只需连接CQLSH并尝试以下命令|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1988309|描述表格；或|1988310|DESC模式；|1988311|此外，您还可以'desc键空间；‘和’使用键空间；‘在那里，您希望看到表’描述表；‘|1988312|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

Just connect CQLSH and try below commands
describe tables; or
DESC SCHEMA ;
Also you can 'desc keyspaces;' and 'use keyspace;' where you want to see the tables with 'describe tables;'

There are many tables in cassandra database, which contain column titled user_id. The values user_id are referred to user stored in table users. As some users are deleted, I would like to delete orphan records in all tables that contain column titled user_id.

Is there a way to list all tables using CassandraSQLContext or any other built-in method or custom procedure in order to avoid explicitly defining the list of tables?

How to list all cassandra tables

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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cassandra数据库中有许多表，其中包含名为user_id的列。user_id值引用到存储在表用户中的用户。由于一些用户被删除，我希望删除所有包含名为user_id的列的表中的孤立记录。是否有方法使用CassandraSQLContext或任何其他内置方法或自定义过程列出所有表，以避免显式定义表列表？

问如何列出所有cassandra表
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问如何列出所有cassandra表
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