[tcapulusdb knowledge base] Introduction to tcapulusdb restrictions

In order to save resources 、 Improve performance and system stability , Database products often have some limitations ,TcaplusDB No exception .

TcaplusDB Support 2 Types of tables ,protobuf(Protocol Buffers) surface TDR(Tencent Data Representation) surface .Protobuf yes Google A descriptive language developed , Serializing structured data , At the same time, it emphasizes simplicity and performance ; TDR It is a cross platform data representation language developed by Tencent , Combined with the XML, Binary sum ORM（ Object relation mapping ） The advantages of , It is widely used in Tencent game data serialization scenarios . among ,TDR Tables support common (generic) Tables and lists (list) surface . generic A table is a table that represents the attributes of an element in the form of a table , For example, students , employer , Game player . list A table is a series of records , For example, game leaderboards , Email in the game （ It's usually the latest 100 Messages ）.

The limitations are as follows ：

Number	resources	ceiling
1	The number of tables allowed in a single table group	256
2	Sub key (shard key )	1
3	Monomorphic Shard Count	10,000
4	single shard size	256GB
5	Single table size	2.56PB
6	generic Table primary key fields	4
7	generic Table non primary key field	128
8	list Table primary key fields	3
9	list Table non primary key field	127
10	list The number of records in the table	1024
11	Table index	8
12	Field length ( Also called attribute length )	32B
13	Primary key field length	1KB
14	Length of non primary key field	256KB
15	Single record size	1MB
16	Number of single index associated records	unlimited
17	The number of table groups allowed to be distributed in a single table ( The same table can be distributed in one table group or in multiple table groups )	8
18	The number of returned records in batch query	1024

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TcaplusDB It's a distributed product of Tencent NoSQL database , The code for storage and scheduling is completely self-developed . With cache + Landing fusion architecture 、PB Levels of storage 、 Millisecond delay 、 Lossless horizontal expansion and complex data structure . At the same time, it has rich ecological environment 、 Easy migration 、 Extremely low operation and maintenance costs and five nine high availability features . Customer coverage game 、 Internet 、 government affairs 、 Finance 、 Manufacturing and the Internet of things .