v3.0

About MogDB
- MogDB Introduction
- Comparison Between MogDB and openGauss
- MogDB Release Notes
- Open Source Components
- Usage Limitations
- Terms of Use
Quick Start
- MogDB Playground
- Container-based MogDB Installation
- Installation on a Single Node
- MogDB Access
  - Use CLI to Access MogDB
    - gsql
    - pgcli
  - Use GUI to Access MogDB
  - Use Middleware to Access MogDB
    - Use WebLogic to Configure MogDB Data Sources
    - Use WebSphere to Configure MogDB Data Sources
  - Use Programming Language to Access MogDB
    - Java
    - C/C++
    - Python
    - Go
    - Rust
    - NodeJS
    - .Net
- Using Sample Dataset Mogila
Characteristic Description
Installation Guide
- Installation Preparation
  - Environment Requirement
  - Operating System Configuration
- Container Installation
- PTK-based Installation
- OM-based Installation
- Manual Installation
- Recommended Parameter Settings
Administrator Guide
AI Features Guide
- AI Features Overview
- AI4DB: Autonomous Database O&M
  - DBMind Mode
  - Components that Support DBMind
    - Prometheus Exporter
  - AI Sub-functions of the DBMind
    - X-Tuner: Parameter Tuning and Diagnosis
    - Index-advisor: Index Recommendation
    - AI4DB: Root Cause Analysis for Slow SQL Statements
    - AI4DB: Trend Prediction
    - SQLdiag: Slow SQL Discovery
- DB4AI: Database-driven AI
  - Native DB4AI Engine
  - Full-process AI
    - PLPython Fenced Mode
    - DB4AI-Snapshots for Data Version Management
- AI in DB
  - Intelligence Explain: SQL Statement Query Time Prediction
Security Guide
- Database Security Management
Developer Guide
- Application Development Guide
  - Development Specifications
  - Development Based on JDBC
  - Development Based on ODBC
  - Development Based on libpq
    - Dependent Header Files of libpq
    - Development Process
    - Example
    - Link Parameters
    - libpq API Reference
      - Database Connection Control Functions
        Description
        PQconnectdbParams
        PQconnectdb
        PQconninfoParse
        PQconnectStart
        PQerrorMessage
        PQsetdbLogin
        PQfinish
        PQreset
        PQstatus
      - Database Statement Execution Functions
        PQclear
        PQexec
        PQexecParams
        PQexecParamsBatch
        PQexecPrepared
        PQexecPreparedBatch
        PQfname
        PQgetvalue
        PQnfields
        PQntuples
        PQprepare
        PQresultStatus
      - Functions for Asynchronous Command Processing
        Description
        PQsendQuery
        PQsendQueryParams
        PQsendPrepare
        PQsendQueryPrepared
        PQflush
      - Functions for Canceling Queries in Progress
        PQgetCancel
        PQfreeCancel
        PQcancel
  - Psycopg-Based Development
  - Commissioning
- Stored Procedure
- User Defined Functions
- PL/pgSQL-SQL Procedural Language
  - Overview of PL/pgSQL Functions
  - Data Types
  - Data Type Conversion
  - Arrays and Records
  - DECLARE Syntax
  - Basic Statements
  - Dynamic Statements
  - Control Statements
  - Transaction Management
  - Other Statements
  - Cursors
  - Advanced Packages
    - Basic Interfaces
      - PKG_SERVICE
  - Retry Management
  - Debugging
  - package
- Scheduled Jobs
  - PKG_SERVICE API
- Autonomous Transaction
- Logical Replication
  - Logical Decoding
    - Overview
    - Logical Decoding by SQL Function Interfaces
  - Publication-Subscription
- Foreign Data Wrapper
- Materialized View
  - Materialized View Overview
  - Full Materialized View
  - Incremental Materialized View
- Partition Management
  - Partition Pruning
  - Recommendations For Choosing A Partitioning Strategy
Performance Tuning Guide
Reference Guide
Common Faults and Identification
- Common Fault Locating Methods
- Common Fault Locating Cases
  - Core Fault Locating
  - Permission/Session/Data Type Fault Location
  - Service/High Availability/Concurrency Fault Location
  - Table/Partition Table Fault Location
    - Table Size Does not Change After VACUUM FULL Is Executed on the Table
    - An Error Is Reported When the Table Partition Is Modified
  - File System/Disk/Memory Fault Location
  - SQL Fault Location
  - Index Fault Location
Source Code Parsing
FAQs
Glossary
Mogeaver
- Overview
- Release Notes

Mathematical Functions and Operators

Numeric Operators

Description: Addition

Example:

MogDB=# SELECT 2+3 AS RESULT;
 result
--------
      5
(1 row)

Description: Subtraction

Example:

MogDB=# SELECT 2-3 AS RESULT;
 result
--------
     -1
(1 row)

Description: Multiplication

Example:

MogDB=# SELECT 2*3 AS RESULT;
 result
--------
      6
(1 row)

Description: Division (The result is not rounded.)

Example:

MogDB=# SELECT 4/2 AS RESULT;
 result
--------
      2
(1 row)

MogDB=# SELECT 4/3 AS RESULT;
      result
------------------
 1.33333333333333
(1 row)

+/-

Description: Positive/Negative

Example:

MogDB=# SELECT -2 AS RESULT;
 result
--------
     -2
(1 row)

Description: Model (to obtain the remainder)

Example:

MogDB=# SELECT 5%4 AS RESULT;
 result
--------
      1
(1 row)

Description: Absolute value

Example:

MogDB=# SELECT @ -5.0 AS RESULT;
 result
--------
    5.0
(1 row)

Description: Power (exponent calculation)

Example:

MogDB=# SELECT 2.0^3.0 AS RESULT;
       result
--------------------
 8.0000000000000000
(1 row)

Description: Square root

Example:

MogDB=# SELECT |/ 25.0 AS RESULT;
 result
--------
      5
(1 row)

||/

Description: Cubic root

Example:

MogDB=# SELECT ||/ 27.0 AS RESULT;
 result
--------
      3
(1 row)

Description: Factorial

Example:

MogDB=# SELECT 5! AS RESULT;
 result
--------
    120
(1 row)

Description: Factorial (prefix operator)

Example:

MogDB=# SELECT !!5 AS RESULT;
 result
--------
    120
(1 row)

Description: Binary AND

Example:

MogDB=# SELECT 91&15  AS RESULT;
 result
--------
     11
(1 row)

Description: Binary OR

Example:

MogDB=# SELECT 32|3  AS RESULT;
 result
--------
     35
(1 row)

Description: Binary XOR

Example:

MogDB=# SELECT 17#5  AS RESULT;
 result
--------
     20
(1 row)

Description: Binary NOT

Example:

MogDB=# SELECT ~1 AS RESULT;
 result
--------
     -2
(1 row)

Description: Binary shift left

Example:

MogDB=# SELECT 1<<4 AS RESULT;
 result
--------
     16
(1 row)

Description: Binary shift right

Example:

MogDB=# SELECT 8>>2 AS RESULT;
 result
--------
      2
(1 row)

Numeric Operation Functions

abs(x)

Description: Absolute value

Return type: same as the input

Example:
```
MogDB=# SELECT abs(-17.4);
 abs
------
 17.4
(1 row)
```

acos(x)

Description: Arc cosine

Return type: double precision

Example:

MogDB=# SELECT acos(-1);
       acos
------------------
 3.14159265358979
(1 row)

asin(x)

Description: Arc sine

Return type: double precision

Example:

MogDB=# SELECT asin(0.5);
       asin
------------------
 .523598775598299
(1 row)

atan(x)

Description: Arc tangent

Return type: double precision

Example:

MogDB=# SELECT atan(1);
       atan
------------------
 .785398163397448
(1 row)

atan2(y, x)

Description: Arc tangent of y/x

Return type: double precision

Example:

MogDB=# SELECT atan2(2, 1);
      atan2
------------------
 1.10714871779409
(1 row)

bitand(integer, integer)

Description: Performs an AND (&) operation on two integers.

Return type: bigint

Example:
```
MogDB=# SELECT bitand(127, 63);
 bitand
--------
     63
(1 row)
```
cbrt(dp)

Description: Cubic root

Return type: double precision

Example:
```
MogDB=# SELECT cbrt(27.0);
 cbrt
------
    3
(1 row)
```
ceil(x)

Description: Minimum integer greater than or equal to the parameter

Return type: integer

Example:
```
MogDB=# SELECT ceil(-42.8);
 ceil
------
  -42
(1 row)
```
ceiling(dp or numeric)

Description: Minimum integer (alias of ceil) greater than or equal to the parameter

Return type: dp or numeric. If implicit type conversion is not considered, the return type is the same as the input type.

Example:
```
MogDB=# SELECT ceiling(-95.3);
 ceiling
---------
     -95
(1 row)
```

cos(x)

Description: Cosine

Return type: double precision

Example:

MogDB=# SELECT cos(-3.1415927);
        cos
-------------------
 -.999999999999999
(1 row)

cot(x)

Description: Cotangent

Return type: double precision

Example:

MogDB=# SELECT cot(1);
       cot
------------------
 .642092615934331
(1 row)

degrees(dp)

Description: Converts radians to angles.

Return type: double precision

Example:

MogDB=# SELECT degrees(0.5);
     degrees
------------------
 28.6478897565412
(1 row)

div(y numeric, x numeric)

Description: Integer part of y/x

Return type: numeric

Example:
```
MogDB=# SELECT div(9,4);
 div
-----
   2
(1 row)
```
exp(x)

Description: Natural exponent

Return type: dp or numeric. If implicit type conversion is not considered, the return type is the same as the input type.

Example:
```
MogDB=# SELECT exp(1.0);
        exp
--------------------
 2.7182818284590452
(1 row)
```
floor(x)

Description: Not larger than the maximum integer of the parameter

Return type: Maximum integer not larger than the parameter

Example:
```
MogDB=# SELECT floor(-42.8);
 floor
-------
   -43
(1 row)
```
int1(in)

Description: Converts the input text parameter to a value of the int1 type and returns the value.

Return type: int1

Example:
```
MogDB=# select int1('123');
 int1
------
 123
(1 row)
MogDB=# select int1('a');
 int1
------
   0
(1 row)
```
int2(in)

Description: Converts the input parameter to a value of the int2 type and returns the value.

The supported input parameter types include float4, float8, int16, numeric, and text.

Return type: int2

Example:
```
MogDB=# select int2('1234');
 int2
------
 1234
(1 row)
MogDB=# select int2(25.3);
 int2
------
   25
(1 row)
```
int4(in)

Description: Converts the input parameter to a value of the int4 type and returns the value.

The supported input parameter types include bit, boolean, char, double precision, int16, numeric, real, smallint and text

Return type: int4

Example:
```
MogDB=# select int4('789');
 int4
------
 789
(1 row)
MogDB=# select int4(99.9);
 int4
------
   99
(1 row)
```
float4(in)

Description: Converts the input parameter to a value of the float4 type and returns the value. The supported input parameter types include bigint, duoble precision, int16, integer, numeric, smallint, and text.

Return type: float4

Example:
```
MogDB=# select float4('789');
 float4
--------
    789
(1 row)
    
MogDB=# select float4(99.9);
 float4
--------
   99.9
(1 row)
```
float8(in)

Description: Converts the input parameter to a value of the float8 type and returns the value. The supported input parameter types include bigint, int16, integer, numeric, real, smallint, and text.

Return type: float8

Example:
```
MogDB=# select float8('789');
 float8
--------
    789
(1 row)
    
MogDB=# select float8(99.9);
 float8
--------
   99.9
(1 row)
```
int16(in)

Description: Converts the input parameter to a value of the int16 type and returns the value. The supported input parameter types include bigint, boolean, double precision, integer, numeric, oid, real, smallint, and tinyint.

Return type: int16

Example:
```
MogDB=# select int16('789');
 int16
--------
    789
(1 row)
    
MogDB=# select int16(99.9);
 int16
--------
   99
(1 row)
```
numeric(in)

Description: Converts the input parameter to a value of the numeric type and returns the value. The supported input parameter types include bigint, boolean, double precision, int16, integer, money, real, and smallint.

Return type: numeric

Example:
```
MogDB=# select "numeric"('789');
 numeric
---------
     789
(1 row)
    
MogDB=# select "numeric"(99.9);
 numeric
---------
    99.9
(1 row)
```
oid(in)

Description: Converts the input parameter to a value of the oid type and returns the value. The supported input parameter types include bigint and int16.

Return type: oid

radians(dp)

Description: Converts angles to radians.

Return type: double precision

Example:

MogDB=# SELECT radians(45.0);
     radians
------------------
 .785398163397448
(1 row)

random()

Description: Random number between 0.0 and 1.0

Return type: double precision

Example:

MogDB=# SELECT random();
      random
------------------
 .824823560658842
(1 row)

multiply(x double precision or text, y double precision or text)

Description: Product of x and y.

Return type: double precision

Example:

MogDB=# SELECT multiply(9.0, '3.0');
     multiply
-------------------
               27
(1 row)
MogDB=# SELECT multiply('9.0', 3.0);
     multiply
-------------------
               27
(1 row)

ln(x)

Description: Natural logarithm

Return type: dp or numeric. If implicit type conversion is not considered, the return type is the same as the input type.

Example:
```
MogDB=# SELECT ln(2.0);
        ln
-------------------
 .6931471805599453
(1 row)
```

log(x)

Description: Logarithm with 10 as the base

Return type: same as the input

Example:

MogDB=# SELECT log(100.0);
        log
--------------------
 2.0000000000000000
(1 row)

log(b numeric, x numeric)

Description: Logarithm with b as the base

Return type: numeric

Example:

MogDB=# SELECT log(2.0, 64.0);
        log
--------------------
 6.0000000000000000
(1 row)

mod(x,y)

Description: Remainder of x/y (model) If x equals to 0, 0 is returned.

Return type: same as the parameter type

Example:
```
MogDB=# SELECT mod(9,4);
 mod
-----
   1
(1 row)
```
```
MogDB=# SELECT mod(9,0);
 mod
-----
   9
(1 row)
```

pi()

Description: π constant value

Return type: double precision

Example:

MogDB=# SELECT pi();
        pi
------------------
 3.14159265358979
(1 row)

power(a double precision, b double precision)

Description: b power of a

Return type: double precision

Example:

MogDB=# SELECT power(9.0, 3.0);
        power
----------------------
 729.0000000000000000
(1 row)

round(x)

Description: Integer closest to the input parameter

Return type: same as the input

Example:

MogDB=# SELECT round(42.4);
 round
-------
    42
(1 row)

MogDB=# SELECT round(42.6);
 round
-------
    43
(1 row)

round(v numeric, s int)

Description:s digits are kept after the decimal point.

Return type: numeric

Example:
```
MogDB=# SELECT round(42.4382, 2);
 round
-------
 42.44
(1 row)
```
setseed(dp)

Description: Sets seed for the following random() invoking (between -1.0 and 1.0, inclusive).

Return type: void

Example:
```
MogDB=# SELECT setseed(0.54823);
 setseed
---------

(1 row)
```
sign(x)

Description: returns symbols of this parameter.

Return type: -1 indicates minus. 0 indicates 0, and 1 indicates positive numbers.

Example:
```
MogDB=# SELECT sign(-8.4);
 sign
------
   -1
(1 row)
```

sin(x)

Description: Sine

Return type: double precision

Example:

MogDB=# SELECT sin(1.57079);
       sin
------------------
 .999999999979986
(1 row)

sqrt(x)

Description: Square root

Return type: dp or numeric. If implicit type conversion is not considered, the return type is the same as the input type.

Example:
```
MogDB=# SELECT sqrt(2.0);
       sqrt
-------------------
 1.414213562373095
(1 row)
```

tan(x)

Description: Tangent

Return type: double precision

Example:

MogDB=# SELECT tan(20);
       tan
------------------
 2.23716094422474
(1 row)

trunc(x)

Description: Truncates (the integral part).

Return type: same as the input

Example:
```
MogDB=# SELECT trunc(42.8);
 trunc
-------
    42
(1 row)
```
trunc(v numeric, s int)

Description: Truncates a number with s digits after the decimal point.

Return type: numeric

Example:
```
MogDB=# SELECT trunc(42.4382, 2);
 trunc
-------
 42.43
(1 row)
```
smgrne(a smgr, b smgr)

Description: Compares two integers of the smgr type to check whether they are different.

Return type: Boolean
smgreq(a smgr, b smgr)

Description: Compares two integers of the smgr type to check whether they are equivalent.

Return type: Boolean
int1abs

Description: Returns the absolute value of data of the uint8 type.

Parameter: tinyint

Return type: tinyint
int1and

Description: Returns the bitwise AND result of two data records of the uint8 type.

Parameter: tinyint, tinyint

Return type: tinyint
int1cmp

Description: Returns the comparison result of two data records of the uint8 type. If the value of the first parameter is greater, 1 is returned. If the value of the second parameter is greater, -1 is returned. If they are the same, 0 is returned.

Parameter: tinyint, tinyint

Return type: integer
int1div

Description: Returns the result of dividing two data records of the uint8 type. The result is of the float8 type.

Parameter: tinyint, tinyint

Return type: tinyint
int1eq

Description: Compares two pieces of data of the uint8 type to check whether they are the same.

Parameter: tinyint, tinyint

Return type: Boolean
int1ge

Description: Determines whether the value of the first parameter is greater than or equal to the value of the second parameter in two data records of the uint8 type.

Parameter: tinyint, tinyint

Return type: Boolean
int1gt

Description: Performs a greater-than operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: Boolean
int1larger

Description: Returns the maximum value of an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1le

Description: Performs a less-than or an equal-to operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: Boolean
int1lt

Description: Performs a less-than operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: Boolean
int1smaller

Description: Calculates the minimum value of an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1inc

Description: Unsigned 1-byte integer plus 1.

Parameter: tinyint

Return type: tinyint
int1mi

Description: Performs a minus operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1mod

Description: Performs a reminder operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1mul

Description: Performs a multiplication operation on unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1ne

Description: Performs a not-equal-to operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: Boolean
int1pl

Description: Performs an addition operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1um

Description: Returns an unsigned 2-byte integer after subtracting the opposite number from the unsigned 1-byte integer.

Parameter: tinyint

Return type: smallint
int1xor

Description: Performs an exclusive OR operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
cash_div_int1

Description: Performs a division operation on the money type.

Parameter: money, tinyint

Return type: money
cash_mul_int1

Description: Performs a multiplication operation on the money type.

Parameter: money, tinyint

Return type: money
int1not

Description: Reverts binary bits of an unsigned 1-byte integer.

Parameter: tinyint

Return type: tinyint
int1or

Description: Performs an OR operation on an unsigned 1-byte integer.

Parameter: tinyint, tinyint

Return type: tinyint
int1shl

Description: Shifts an unsigned 1-byte integer leftwards by a specified number of bits.

Parameter: tinyint, integer

Return type: tinyint
width_bucket(op numeric, b1 numeric, b2 numeric, count int)

Description: Returns a bucket to which the operand will be assigned in an equi-depth histogram with count buckets, ranging from b1 to b2.

Return type: int

Example:
```
MogDB=# SELECT width_bucket(5.35, 0.024, 10.06, 5);
 width_bucket
--------------
            3
(1 row)
```
width_bucket(op dp, b1 dp, b2 dp, count int)

Description: Returns a bucket to which the operand will be assigned in an equi-depth histogram with count buckets, ranging from b1 to b2.

Return type: int

Example:
```
MogDB=# SELECT width_bucket(5.35, 0.024, 10.06, 5);
 width_bucket
--------------
            3
(1 row)
```

Issue