GBase 8a MPP Cluster 产品手册 4 管理员指南 文档版本953(2022-04-10) 南大通用数据技术股份有限公司 450 +------+-----------+----------+-------------+ 1 row in set (Elapsed: 00:00:00.00)
Efficient Transparent Compression Efficient and transparent compression technology can automatically select the optimal compression algorithm based on data type and distribution, minimizing the storage space required, reducing I/O consumption, and improving query performance. It supports compression options at the library, table, and column levels, balancing performance and compression ratio flexibly, and the compression and decompression process is transparent to users. From the perspective of saving I/O resources, for analysis systems where I/O is the main bottleneck, efficient and transparent compression technology can bring about a performance improvement of about an order of magnitude compared to traditional row-based databases.
GBase 8a MPP Cluster Technical White Paper General Data Technology Co., Ltd. - 11 - Figure 3-2. Adaptive Transparent Compression Diagram. 1) Compression ratio can reach 1:2 to 1:20 or even better, much higher than row storage; 2) Save 50% to 95% of storage space, greatly reducing data processing energy consumption; 3) Built-in dozens of different levels of compression algorithms, automatically select the best compression algorithm according to data characteristics; 4) The I/O requirements are greatly reduced in the compressed state, and data loading and query performance are significantly improved.
对于表和字段权限的授予和收回示例如下: 1. INSERT GRANT DBA TO user1; GRANT DBA TO usera, userb, userc; REVOKE DBA FROM user1; REVOKE DBA FROM usera, userb, userc; ALL PRIVILEGES INSERT DELETE ON , UPDATE REFERENCES SELECT column ( ) , ALTER INDEX UNDER table view synonym owner .
5. REFERENCES GRANT INSERT ON customer_table TO user1; GRANT INSERT ON customer_table TO usera, userb, userc; GRANT INSERT ON customer_table TO PUBLIC; REVOKE INSERT ON customer_table FROM PUBLIC; REVOKE INSERT ON customer_table FROM usera, userb, userc; REVOKE INSERT ON customer_table FROM user1; GRANT DELETE ON customer_table TO user1; GRANT DELETE ON customer_table TO usera, userb, userc; GRANT DELETE ON customer_table TO PUBLIC; REVOKE DELETE ON customer_table FROM PUBLIC; REVOKE DELETE ON customer_table FROM usera, userb, userc; REVOKE DELETE ON customer_table FROM user1; GRANT SELECT ON customer_table TO usera, userb, userc; GRANT SELECT (customer_id, customer_name) ON customer_table TO PUBLIC; REVOKE SELECT (customer_id, customer_name) ON customer_table FROM PUBLIC; REVOKE SELECT ON customer_table FROM usera, userb, userc; GRANT UPDATE ON customer_table TO usera, userb, userc; GRANT UPDATE (customer_id, customer_name) ON customer_table TO PUBLIC; REVOKE UPDATE (customer_id, customer_name) ON customer_table FROM PUBLIC; REVOKE UPDATE ON customer_table FROM usera, userb, userc;
收回权限语法示例如下: GRANT REFERENCES ON customer_table TO usera, userb, userc; GRANT REFERENCES (customer_id, customer_name) ON customer_table TO PUBLIC; REVOKE REFERENCES (customer_id, customer_name) ON customer_table FROM PUBLIC; REVOKE REFERENCES ON customer_table FROM usera, userb, userc; GRANT INDEX ON customer_table TO usera, userb, userc; GRANT INDEX ON customer_table TO PUBLIC; REVOKE INDEX ON customer_table FROM PUBLIC; REVOKE INDEX ON customer_table FROM usera, userb, userc; GRANT ALTER ON customer_table TO usera, userb, userc; GRANT ALTER ON customer_table TO PUBLIC; REVOKE ALTER ON customer_table FROM PUBLIC; REVOKE ALTER ON customer_table FROM usera, userb, userc; GRANT ALL ON customer_table TO usera, userb, userc; GRANT ALL ON customer_table TO PUBLIC;