简体繁体 English

DynamoDb 非依赖属性的多条件更新

[英]DynamoDb Multiple Conditional Updates of Non-dependant Attributes

原文 2023-01-26 12:01:35 5 1 amazon-dynamodb/ aws-sdk-js

I am using the Javascript SDK for AWS and I am attempting to perform a single update operation on OHLC (Open, High, Low, Close) data and I only want to update the "High" attribute if the new value is higher than the stored value and the opposite for the "Low".我正在为 AWS 使用 Javascript SDK，我正在尝试对 OHLC（开盘价、高价、低价、收盘价）数据执行单个更新操作，如果新值高于存储的值，我只想更新“高”属性价值和相反的“低”。

As far as I can tell, there are 2 options:据我所知，有两种选择：

Query the dB to get the current OHLC, calculate the differences, then update the dB again.查询 dB 以获取当前 OHLC，计算差异，然后再次更新 dB。
Perform 2 updates, one with the conditional expression for "High" and one for the "Low" conditional expression.执行 2 次更新，一次使用“高”条件表达式，一次使用“低”条件表达式。

The basis of the question is this: "Can I use the conditionExpression to perform multiple, non-dependant update conditions on seperate attributes?"问题的基础是：“我可以使用 conditionExpression 对单独的属性执行多个非依赖更新条件吗？”

1 个解决方案

I'm afraid its not possible to have 2 non-dependent conditions on the same UpdateItem API call.恐怕在同一个UpdateItem API 调用中不可能有 2 个非依赖条件。

Your first options is more cost effective, however, you may need to use versioning if you have high concurrency.您的第一个选项更具成本效益，但是，如果您具有高并发性，则可能需要使用版本控制。