From e5b121d649bf3430e1957b9c5449a85f6de12fbf Mon Sep 17 00:00:00 2001 From: Jeff Tao Date: Sun, 4 Aug 2019 20:30:37 +0800 Subject: [PATCH] Update advanced features.md --- documentation/webdocs/markdowndocs/advanced features.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/documentation/webdocs/markdowndocs/advanced features.md b/documentation/webdocs/markdowndocs/advanced features.md index 05f6da5ed9..bc3dc9b397 100644 --- a/documentation/webdocs/markdowndocs/advanced features.md +++ b/documentation/webdocs/markdowndocs/advanced features.md @@ -62,7 +62,7 @@ Time series data is a sequence of data points over time. Inside a table, the dat To reduce the development complexity and improve data consistency, TDengine provides the pub/sub functionality. To publish a message, you simply insert a record into a table. Compared with popular messaging tool Kafka, you subscribe to a table or a SQL query statement, instead of a topic. Once new data points arrive, TDengine will notify the application. The process is just like Kafka. -The detailed API will be introduced in the [connectors](https://www.taosdata.com/en/documentation/advanced-features/) section. +The detailed API will be introduced in the [connectors](https://www.taosdata.com/en/documentation/connector/) section. ##Caching TDengine allocates a fixed-size buffer in memory, the newly arrived data will be written into the buffer first. Every device or table gets one or more memory blocks. For typical IoT scenarios, the hot data shall always be newly arrived data, they are more important for timely analysis. Based on this observation, TDengine manages the cache blocks in First-In-First-Out strategy. If no enough space in the buffer, the oldest data will be saved into hard disk first, then be overwritten by newly arrived data. TDengine also guarantees every device can keep at least one block of data in the buffer. @@ -77,4 +77,4 @@ By this design, caching tool, like Redis, is not needed in the system. It will r TDengine creates one or more virtual nodes(vnode) in each data node. Each vnode contains data for multiple tables and has its own buffer. The buffer of a vnode is fully separated from the buffer of another vnode, not shared. But the tables in a vnode share the same buffer. -System configuration parameter cacheBlockSize configures the cache block size in bytes, and another parameter cacheNumOfBlocks configures the number of cache blocks. The total memory for the buffer of a vnode is $cacheBlockSize \times cacheNumOfBlocks$. Another system parameter numOfBlocksPerMeter configures the maximum number of cache blocks a table can use. When you create a database, you can specify these parameters. \ No newline at end of file +System configuration parameter cacheBlockSize configures the cache block size in bytes, and another parameter cacheNumOfBlocks configures the number of cache blocks. The total memory for the buffer of a vnode is $cacheBlockSize \times cacheNumOfBlocks$. Another system parameter numOfBlocksPerMeter configures the maximum number of cache blocks a table can use. When you create a database, you can specify these parameters. -- GitLab