Distribution Column Recommendation Functions
Distribution column recommendation is used to recommend distribution columns and distribution modes in a distributed database. The purpose is to reduce the labor cost of selecting distribution columns during service migration or rollout.
- sqladvisor.init(char, boolean, boolean, boolean, int, int)
Description: Initializes parameters.
Return type: Boolean
Parameter |
Type |
Description |
Mandatory or Not |
|---|---|---|---|
kind |
char |
Recommendation type. Currently, this parameter can only be set to D. |
Yes |
isUseCost |
boolean |
Indicates whether optimizers are used. If data is available, optimizers are used. |
Yes |
isUseCollect |
boolean |
Indicates whether the analysis is started from the collected load. The default value is false. |
No |
isConstraintPrimaryKey |
boolean |
Indicates whether primary key constraints are retained. The default value is true. |
No |
sqlCount |
int |
Number of collected SQL statements. The default value is 10000. The value ranges from 1 to 100000. |
No |
maxMemory |
int |
Maximum memory occupied by distribution column recommendation. The default value is 1024. The value ranges from 1 to 10240, in MB. |
No |
- sqladvisor.set_weight_params(real, real, real)
Description: Sets the weight of different components in heuristic rules. A default parameter is set when the init function is invoked. This function does not need to be invoked during analysis.
Return type: Boolean
Parameter |
Type |
Description |
Mandatory or Not |
|---|---|---|---|
joinWeight |
real |
Weight of JOIN. The value ranges from 0 to 1000. |
Yes |
goupbyWeight |
real |
Weight of GROUP BY. The value ranges from 0 to 1000. |
Yes |
qualWeight |
real |
Weight of predicate. The value ranges from 0 to 1000. |
Yes |
This function is optional. When the init function is executed, the default weights of JOIN, GROUP BY, and predicate are preset to 1.0, 0.1, and 0.05, respectively.
- sqladvisor.set_cost_params(bigint, boolean, text)
Description: Parameter that can be set in the Whtif cost model.
Return type: Boolean
Parameter |
Type |
Description |
Mandatory or Not |
|---|---|---|---|
maxTime |
bigint |
Maximum recommendation duration, in minutes. If the value is less than or equal to 0, the duration is not limited by default. |
Yes |
isTotalSQL |
boolean |
Indicates whether all SQL statements are used for calculation. The value true indicates that all SQL statements are used for calculation. The value false indicates that SQL statements whose cost is too high or too low are filtered out based on the percentile. |
Yes |
compressLevel |
text |
Search space size of the recommendation algorithm. The options are low, med, and high. |
Yes |
- This function is optional. When the init function is executed, maxTime is preset to –1, isTotalSQL is preset to true, and compressLevel is preset to high.
- A lower compression level indicates longer time, and it is more likely that a better result can be achieved.
- sqladvisor.assign_table_type(text)
Description: Specifies a table as a replication table.
Parameter: table name
Return type: Boolean
The specified replication table must be used before analyze_query and analyze_workload are invoked.
- sqladvisor.analyze_query(text, int)
Description: Imports SQL statements to be recommended and analyzes the components of the statements.
Return type: Boolean
Parameter |
Type |
Description |
Mandatory or Not |
|---|---|---|---|
query |
text |
SQL statement |
Yes |
frequency |
int |
Frequency of a statement in the load. The default value is 1. The value ranges from 1 to 2147483647. |
No |
- If the value of the query parameter contains special characters, such as single quotation marks ('), you can use single quotation marks (') to escape the special characters.
- This function is not supported in semi-online mode.
- sqladvisor.analyze_workload()
Description: Analyzes the load information collected online.
Return type: Boolean
- sqladvisor.get_analyzed_result(text)
Description: Obtains beneficial components extracted from the current table.
Parameter: text
Return type: record
The following table describes return fields.
Name |
Type |
Description |
|---|---|---|
schema_name |
text |
Schema name |
table_name |
text |
Table name |
col_name |
text |
Column name |
operator |
text |
Operator type |
count |
int |
Number of times that an operator is used |
- sqladvisor.run()
Description: Performs calculation and analysis based on the specified schema and input SQL statements.
Return type: Boolean
- sqladvisor.get_distribution_key()
Description: Obtains the recommendation result.
The analysis result is saved in a session. If the session disconnects, the result will be lost.
Return type: record
The following table describes return fields.
Name |
Type |
Description |
|---|---|---|
db_name |
text |
Database name |
schema_name |
text |
Schema name |
table_name |
text |
Table name |
distribution_type |
text |
Recommended distribution type |
distribution_key |
text |
Recommended distribution column |
start_time |
timestamp |
Recommended start time |
end_time |
timestamp |
Recommended end time |
cost_improve |
text |
Cost increase brought by the recommendation result |
comment |
text |
Comment |
- sqladvisor.clean()
Description: Clears all the memory in the recommendation process of a session.
Return type: Boolean
- sqladvisor.start_collect_workload(int, int)
Description: Starts online load collection.
Return type: Boolean
Parameter |
Type |
Description |
Mandatory or Not |
|---|---|---|---|
sqlCount |
int |
Maximum number of SQL statements for online load collection. The value ranges from 1 to 100000 and the default value is 10000. |
Yes |
maxMemory |
int |
Maximum memory occupied by online load collection. The default value is 1024. The value ranges from 1 to 10240, in MB. |
Yes |
- The online collection function can be invoked only by the system administrator.
- The load of only one database can be collected at a time.
- Currently, only common SQL statements as well as DML and DQL statements in stored procedures are supported.
- sqladvisor.end_collect_workload()
Description: Disables online load collection.
Return type: Boolean
- The online collection function can be disabled only by the system administrator.
- sqladvisor.clean_workload()
Description: Clears the memory in the load.
Return type: Boolean
- The function of clearing memory in the load can be invoked only by the system administrator.
- You must manually execute the cleanup function.
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