The Log Service provides two functions related to the read operation.
Log collection and consumption (LogHub): provides public channels for log collection and distribution, sequential (FIFO) read and write of full data, and functions similar to Kafka.
- Each LogStore has one or more shards. Data is written to a specific shard at random.
- You can read logs in batches from the specified shard according to the log write sequence.
- You can set the starting point (cursor) of batch log pulling from shards based on the time when the Log Service receives logs.
- By default, logs are retained in LogHub for two days, during which logs can be consumed.
LogSearch (index): The LogSearch function is provided based on LogHub and supports massive log query. Data is queried randomly based on keywords.
- Acquisition of only keyword-matched data
- Boolean combination of keywords AND, NOT, and OR
- Data is queried based on all shards.
|Function||LogSearch||Log collection and consumption (based on LogHub)|
|Keyword search||Supported||Not supported|
|Reading of small data volumes||Fast||Fast|
|Full data reading||Slow (100 logs every 100 ms, not recommended)||Fast (1-MB logs every 10 ms, recommended)|
|Reading by topic||Yes||No. Data is read by shard.|
|Reading by shard||No. Data is queried based on all shards.||Yes. A shard must be specified for the read operation.|
|Application scenario||Data filter is performed for monitoring and troubleshooting.||Full processing scenarios such as stream computing and batch processing|