blocks|key|45226|text|使用aws+dynamodb+cli，您可以通过scan获取它，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|45227|aws+dynamodb+scan+--table-name+<TABLE_NAME>+--select+"COUNT"|code-block|syntax|javascript|45228|响应将如下所示：|45229|{
++++"Count":+123,
++++"ScannedCount":+123,
++++"ConsumedCapacity":+null
}|45230|请注意，与describe-table+api相比，此信息是实时的。|45231|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.aws.amazon.com/cli/latest/reference/dynamodb/index.html#cli-aws-dynamodb|1|http://docs.aws.amazon.com/cli/latest/reference/dynamodb/scan.html|2|http://docs.aws.amazon.com/cli/latest/reference/dynamodb/describe-table.html^0|2|G|0|O|4|1|0|0|0|0|5|E|2|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]|$A|14|B|15|1|16]]|C|$]]|$1|D|3|E|5|F|7|17|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|18|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|19|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|1A|8|@]|9|@$A|1B|B|1C|1|1D]]|C|$]]|$1|O|3|-4|5|6|7|1E|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]|W|$5|R|S|T|C|$U|X]]|Y|$5|R|S|T|C|$U|Z]]]]

With the <a href="http://docs.aws.amazon.com/cli/latest/reference/dynamodb/index.html#cli-aws-dynamodb">aws dynamodb cli</a> you can get it via <a href="http://docs.aws.amazon.com/cli/latest/reference/dynamodb/scan.html">scan</a> as follows:

<pre><code>aws dynamodb scan --table-name &lt;TABLE_NAME&gt; --select "COUNT"
</code></pre>

The response will look similar to this:

<pre><code>{
 "Count": 123,
 "ScannedCount": 123,
 "ConsumedCapacity": null
}
</code></pre>

notice that this information is in real time in contrast to the <a href="http://docs.aws.amazon.com/cli/latest/reference/dynamodb/describe-table.html">describe-table</a> api

blocks|key|45379|text|也可以从UI中看到。转到表上的概述选项卡，您将看到项目计数。希望这能帮助到别人。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|45380|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Can be seen from UI as well.
Go to overview tab on table, you will see item count. Hope it helps someone.

blocks|key|4552035|text|替换表名并使用以下查询获取本地环境中的数据：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4552036|aws+dynamodb+scan+--table-name+<TABLE_NAME>+--select+"COUNT"+--endpoint-url+http://localhost:8000|code-block|syntax|javascript|4552037|替换表名并删除端点url以获取生产环境中的数据。|4552038|aws+dynamodb+scan+--table-name+<TABLE_NAME>+--select+"COUNT"|4552039|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|$]]

Replace the table name and use the below query to get the data on your local environment:

<pre><code>aws dynamodb scan --table-name &lt;TABLE_NAME&gt; --select "COUNT" --endpoint-url http://localhost:8000
</code></pre>

Replace the table name and remove the endpoint url to get the data on production environment

<pre><code>aws dynamodb scan --table-name &lt;TABLE_NAME&gt; --select "COUNT"
</code></pre>

blocks|key|4552121|text|我在这里来得太晚了，但我想扩展丹尼尔关于使用aws+cli来包含过滤器表达式的答案。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4552122|正在运行|4552123|aws+dynamodb+scan+\
++++--table-name+<tableName>+\
++++--filter-expression+"#v+=+:num"+\
++++--expression-attribute-names+'{"#v":+"fieldName"}'+\
++++--expression-attribute-values+'{":num":+{"N":+"123"}}'+\
++++--select+"COUNT"|code-block|syntax|javascript|4552124|会给你|4552125|{
++++"Count":+2945,
++++"ScannedCount":+7874,
++++"ConsumedCapacity":+null
}|4552126|也就是说，ScannedCount是总计数，Count是由给定表达式(fieldName=123)过滤的项目数。|4552127|entityMap^0|M|7|0|0|0|0|0|5|C|M|5|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|X|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|11|8|@$9|12|A|13|B|C]|$9|14|A|15|B|C]]|D|@]|E|$]]|$1|S|3|-4|5|6|7|16|8|@]|D|@]|E|$]]]|T|$]]

I'm too late here but like to extend Daniel's answer about using <code>aws cli</code> to include filter expression.
Running
<pre><code>aws dynamodb scan \
 --table-name &lt;tableName&gt; \
 --filter-expression &quot;#v = :num&quot; \
 --expression-attribute-names '{&quot;#v&quot;: &quot;fieldName&quot;}' \
 --expression-attribute-values '{&quot;:num&quot;: {&quot;N&quot;: &quot;123&quot;}}' \
 --select &quot;COUNT&quot;
</code></pre>
would give
<pre><code>{
 &quot;Count&quot;: 2945,
 &quot;ScannedCount&quot;: 7874,
 &quot;ConsumedCapacity&quot;: null
}
</code></pre>
That is, <code>ScannedCount</code> is total count and <code>Count</code> is the number of items which are filtered by given expression (fieldName=123).

blocks|key|4551969|text|如果你碰巧在这里，并且你正在使用C#，下面是代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4551970|var+cancellationToken+=+new+CancellationToken();

var+request+=+new+ScanRequest("TableName")+{Select+=+Select.COUNT};

var+result+=+context.Client.ScanAsync(request,+cancellationToken).Result;

totalCount+=+result.Count;|code-block|syntax|javascript|4551971|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|$]]

If you happen to reach here, and you are working with C#, here is the code:

<pre><code>var cancellationToken = new CancellationToken();

var request = new ScanRequest("TableName") {Select = Select.COUNT};

var result = context.Client.ScanAsync(request, cancellationToken).Result;

totalCount = result.Count;
</code></pre>

blocks|key|4552105|text|我将这个答案发布给任何使用C#的人，他们想要一个功能齐全、经过良好测试的答案，并演示使用查询而不是扫描。特别是，此答案处理要计数的超过1MB大小的项目。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4552106|public+async+Task<int>+GetAvailableCount(string+pool_type,+string+pool_key)
{
++++var+queryRequest+=+new+QueryRequest
++++{
++++++++TableName+=+PoolsDb.TableName,
++++++++ConsistentRead+=+true,
++++++++Select+=+Select.COUNT,
++++++++KeyConditionExpression+=+"pool_type_plus_pool_key+=+:type_plus_key",
++++++++ExpressionAttributeValues+=+new+Dictionary<string,+AttributeValue>+{
++++++++++++{":type_plus_key",+new+AttributeValue+{+S+=++pool_type+%2B+pool_key+}}
++++++++},
++++};
++++var+t0+=+DateTime.UtcNow;
++++var+result+=+await+Client.QueryAsync(queryRequest);
++++var+count+=+result.Count;
++++var+iter+=+0;
++++while+(+result.LastEvaluatedKey+!=+null+&&+result.LastEvaluatedKey.Values.Count+>+0)+
++++{
++++++++iter%2B%2B;
++++++++var+lastkey+=+result.LastEvaluatedKey.Values.ToList()[0].S;
++++++++_logger.LogDebug($"GetAvailableCount+{pool_type}-{pool_key}+iteration+{iter}+instance+key+{lastkey}");
++++++++queryRequest.ExclusiveStartKey+=+result.LastEvaluatedKey;
++++++++result+=+await+Client.QueryAsync(queryRequest);
++++++++count+%2B=+result.Count;
++++}
++++_logger.LogDebug($"GetAvailableCount+{pool_type}-{pool_key}+returned+{count}+after+{iter}+iterations+in+{(DateTime.UtcNow+-+t0).TotalMilliseconds}+ms.");
++++return+count;
}|code-block|syntax|javascript|4552107|}|4552108|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I'm posting this answer for anyone using C# that wants a fully functional, well-tested answer that demonstrates using query instead of scan. In particular, this answer handles more than 1MB size of items to count.
<pre><code>public async Task&lt;int&gt; GetAvailableCount(string pool_type, string pool_key)
{
 var queryRequest = new QueryRequest
 {
 TableName = PoolsDb.TableName,
 ConsistentRead = true,
 Select = Select.COUNT,
 KeyConditionExpression = &quot;pool_type_plus_pool_key = :type_plus_key&quot;,
 ExpressionAttributeValues = new Dictionary&lt;string, AttributeValue&gt; {
 {&quot;:type_plus_key&quot;, new AttributeValue { S = pool_type + pool_key }}
 },
 };
 var t0 = DateTime.UtcNow;
 var result = await Client.QueryAsync(queryRequest);
 var count = result.Count;
 var iter = 0;
 while ( result.LastEvaluatedKey != null &amp;&amp; result.LastEvaluatedKey.Values.Count &gt; 0) 
 {
 iter++;
 var lastkey = result.LastEvaluatedKey.Values.ToList()[0].S;
 _logger.LogDebug($&quot;GetAvailableCount {pool_type}-{pool_key} iteration {iter} instance key {lastkey}&quot;);
 queryRequest.ExclusiveStartKey = result.LastEvaluatedKey;
 result = await Client.QueryAsync(queryRequest);
 count += result.Count;
 }
 _logger.LogDebug($&quot;GetAvailableCount {pool_type}-{pool_key} returned {count} after {iter} iterations in {(DateTime.UtcNow - t0).TotalMilliseconds} ms.&quot;);
 return count;
}
</code></pre>
}

blocks|key|45569|text|如果有人正在寻找一个简单的NodeJS+Lambda计数解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|45570|const+data+=+await+dynamo.scan({+Select:+"COUNT",+TableName:+"table"+}).promise();

//+data.Count+->+number+of+elements+in+table.|code-block|syntax|javascript|45571|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|$]]

If anyone is looking for a straight forward NodeJS Lambda count solution:
<pre><code>const data = await dynamo.scan({ Select: &quot;COUNT&quot;, TableName: &quot;table&quot; }).promise();

// data.Count -&gt; number of elements in table.
</code></pre>

blocks|key|4551987|text|在Scala中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4551988|import+com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder
import+com.amazonaws.services.dynamodbv2.document.DynamoDB
val+client+=+AmazonDynamoDBClientBuilder.standard().build()

val+dynamoDB+=+new+DynamoDB(client)
val+tableDescription+=+dynamoDB.getTable("table+name").describe().getItemCount()|code-block|syntax|javascript|4551989|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|$]]

In Scala:

<pre><code>import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder
import com.amazonaws.services.dynamodbv2.document.DynamoDB
val client = AmazonDynamoDBClientBuilder.standard().build()

val dynamoDB = new DynamoDB(client)
val tableDescription = dynamoDB.getTable("table name").describe().getItemCount()
</code></pre>

blocks|key|45649|text|DynamoDB现在在UI中有一个“Get+Live+Item+Count”按钮。如果您有一个将消耗读容量的大型表，请注意生产方面的注意事项。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|45650|​|45651|📷|atomic|offset|length|45652|45653|45654|45655|45656|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/e6c3e1a383e34d5fb0bcd9caa7644e83.png|imageAlt|1|https://ask.qcloudimg.com/http-save/yehe-900000/3edbfb1d8c74debd3bb46142c94d3c03.png^0|0|0|0|1|0|0|0|0|0|1|1|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Z|8|@]|9|@$G|10|H|11|1|12]]|A|$]]|$1|I|3|C|5|6|7|13|8|@]|9|@]|A|$]]|$1|J|3|C|5|6|7|14|8|@]|9|@]|A|$]]|$1|K|3|E|5|F|7|15|8|@]|9|@$G|16|H|17|1|18]]|A|$]]|$1|L|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T|U|-4]]|V|$5|P|Q|R|A|$S|W|U|-4]]]]

DynamoDB now has a 'Get Live Item Count' button in the UI. Please note the production caveat if you have a large table that will consume read capacity.
<a href="https://i.stack.imgur.com/d7QXp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/d7QXp.png" alt="Live Item Count" /></a>
<a href="https://i.stack.imgur.com/517z7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/517z7.png" alt="Live Item Count" /></a>

blocks|key|4551998|text|您可以使用dynamodb映射器查询。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4551999|PaginatedQueryList<YourModel>+list+=+DymamoDBMapper.query(YourModel.class,+queryExpression);
int+count+=+list.size();|code-block|syntax|javascript|4552000|它调用loadAllResults()来延迟加载下一个可用的结果，直到allResultsLoaded。|offset|length|style|CODE|4552001|参考：https://docs.amazonaws.cn/en_us/amazondynamodb/latest/developerguide/DynamoDBMapper.Methods.html#DynamoDBMapper.Methods.query|4552002|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.amazonaws.cn/en_us/amazondynamodb/latest/developerguide/DynamoDBMapper.Methods.html#DynamoDBMapper.Methods.query^0|0|0|3|G|0|3|3H|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@$I|Z|J|10|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|11|8|@]|9|@$I|12|J|13|1|14]]|A|$]]|$1|O|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

You could use dynamodb mapper query.

<pre><code>PaginatedQueryList&lt;YourModel&gt; list = DymamoDBMapper.query(YourModel.class, queryExpression);
int count = list.size();
</code></pre>

it calls <code>loadAllResults()</code> that would lazily load next available result until allResultsLoaded.

Ref: <a href="https://docs.amazonaws.cn/en_us/amazondynamodb/latest/developerguide/DynamoDBMapper.Methods.html#DynamoDBMapper.Methods.query" rel="nofollow noreferrer">https://docs.amazonaws.cn/en_us/amazondynamodb/latest/developerguide/DynamoDBMapper.Methods.html#DynamoDBMapper.Methods.query</a>

blocks|key|4552064|text|len(response['Items'])|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4552065|将为您提供已筛选行的计数。|unstyled|4552066|哪里,|4552067|fe+=+Key('entity').eq('tesla')
response+=+table.scan(FilterExpression=fe)|4552068|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$B|C]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>len(response['Items'])
</code></pre>

will give you the count of the filtered rows 

where,

<pre><code>fe = Key('entity').eq('tesla')
response = table.scan(FilterExpression=fe)
</code></pre>

blocks|key|4551919|text|我使用scan来获取所需tableName.Following的总数，这是一个Java代码片段|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4551920|Long+totalItemCount+=+0;
do{
++++ScanRequest+req+=+new+ScanRequest();
++++req.setTableName(tableName);

++++if(result+!=+null){
++++++++req.setExclusiveStartKey(result.getLastEvaluatedKey());
++++}

++++result+=+client.scan(req);

++++totalItemCount+%2B=+result.getItems().size();

}+while(result.getLastEvaluatedKey()+!=+null);

System.out.println("Result+size:+"+%2B+totalItemCount);|code-block|syntax|javascript|4551921|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|$]]

I used scan to get total count of the required tableName.Following is a Java code snippet for same

<pre><code>Long totalItemCount = 0;
do{
 ScanRequest req = new ScanRequest();
 req.setTableName(tableName);

 if(result != null){
 req.setExclusiveStartKey(result.getLastEvaluatedKey());
 }

 result = client.scan(req);

 totalItemCount += result.getItems().size();

} while(result.getLastEvaluatedKey() != null);

System.out.println("Result size: " + totalItemCount);
</code></pre>

blocks|key|4551860|text|这是亚马逊网络服务JavaScript软件开发工具包用户的解决方案，对于其他语言几乎是一样的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4551861|Result.data.Count会给你想要的东西|4551862|+apigClient.getitemPost({},+body,+{})

++++.then(function(result){

++++++++var+dataoutput+=+result.data.Items[0];

++++++++console.log(result.data.Count);
++}).catch(+function(result){

});|code-block|syntax|javascript|4551863|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This is solution for AWS JavaScript SDK users, it is almost same for other languages.

Result.data.Count will give you what you are looking for

<pre><code> apigClient.getitemPost({}, body, {})

 .then(function(result){

 var dataoutput = result.data.Items[0];

 console.log(result.data.Count);
 }).catch( function(result){

});
</code></pre>

I want to know item count with DynamoDB querying.

I can querying for DynamoDB, but I only want to know 'total count of item'.

For example, 'SELECT COUNT(*) FROM ... WHERE ...' in MySQL

<pre class="lang-php prettyprint-override"><code>$result = $aws-&gt;query(array(
 'TableName' =&gt; 'game_table',
 'IndexName' =&gt; 'week-point-index',
 'KeyConditions' =&gt; array(
 'week' =&gt; array(
 'ComparisonOperator' =&gt; 'EQ',
 'AttributeValueList' =&gt; array(
 array(Type::STRING =&gt; $week)
 )
 ),
 'point' =&gt; array(
 'ComparisonOperator' =&gt; 'GE',
 'AttributeValueList' =&gt; array(
 array(Type::NUMBER =&gt; $my_point)
 )
 )
 ),
));
echo Count($result['Items']);
</code></pre>

this code gets the all users data higher than my point.

If count of $result is 100,000, $result is too much big.
And it would exceed the limits of the query size.

I need help.

How to get item count from DynamoDB?

软件开发

MySQL

Java

我想知道DynamoDB查询的商品数量。我可以查询DynamoDB，但我只想知道“商品总数”。例如，'SELECT COUNT(*) FROM ... WHERE ...‘在MySQL中$result = $aws->query(array( 'TableName' => 'game_table', 'IndexName' => 'week-point-index', 'KeyConditions

问如何从DynamoDB获取商品数量？
EN

回答 13

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