| 281 | Do not use FLOAT Data Type | Find base table columns that have FLOAT, REAL, or DOUBLE PRECISION type. "The data types real and double precision are inexact, variable-precision numeric types. On all currently supported platforms, these types are implementations of IEEE Standard 754 for Binary Floating-Point Arithmetic (single and double precision, respectively), to the extent that the underlying processor, operating system, and compiler support it." (PostgreSQL documentation) Do not use the approximate numeric types FLOAT, REAL, and DOUBLE PRECISION in order to present fractional numeric data. Due to the use of the IEEE 754 standard the results of calculations with the values, which have one of these types, can be inexact because out of necessity some numbers must be rounded to a value, which is very close. "Comparing two floating-point values for equality might not always work as expected." (PostgreSQL documentation) | Problem detection | INFORMATION_SCHEMA only | 2021-03-12 15:41 | MIT License | |
| 282 | Do not use the money data type | Find base table columns with the Money data type. Each value of the money type has associated currency sign that depends on server settings. It could be $. Moreover, using the values for arithmetic operations requires casts that makes the code more complicated. | Problem detection | INFORMATION_SCHEMA only | 2021-02-25 17:29 | MIT License | |
| 283 | Double checking of the maximum character length | Do not duplicate code. In this case a CHECK constraint duplicates the restriction that is already enforced with the help of the declaration of the maximum field size (for instance, VARCHAR(100)). | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2023-11-18 13:27 | MIT License | |
| 284 | Double negatives in Boolean expressions | Write code that is simple to understand and not confusing. A double negative is a grammatical construction occurring when two forms of negation are used in the same expression (https://en.wikipedia.org/wiki/Double_negative). Double negatives in Boolean expressions make it more difficult to understand and maintain the code. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-02-25 17:29 | MIT License | |
| 285 | Double negatives in regular expressions | Fing regular expression patterns that use [^\S] instead of \s or [^\D] instead of \d or [^\W] instead of \w. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2023-11-09 12:01 | MIT License | |
| 286 | Do you really need fractional seconds? | Find default values that return current timestamp with the maximum number of fractional seconds (6). | Problem detection | INFORMATION_SCHEMA only | 2021-02-25 17:29 | MIT License | |
| 287 | Duplicate CHECK constraints that are connected directly to a table | The same table should not have multiple CHECK constraints with exactly the same Boolean expression. Do remember that the same task can be solved in SQL usually in multiple different ways. Thus, the exact copies are not the only possible duplication. | Problem detection | INFORMATION_SCHEMA only | 2021-02-25 17:30 | MIT License | |
| 288 | Duplicate CHECK constraints that are connected to a domain | The same domain should not have multiple CHECK constraints with exactly the same Boolean expression. Do remember that the same task can be solved in SQL usually in multiple different ways. Thus, the exact copies are not the only possible duplication. | Problem detection | INFORMATION_SCHEMA only | 2021-02-25 17:30 | MIT License | |
| 289 | Duplicate check of empty strings | Find columns that have a check that prevents the empty string in the column but there is already another check on the column that enforces the constraint. If there is a constraint description!~'^[[:space:]]*$', then it covers the constraint description!='' and the latter becomes redundant. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-12-19 15:08 | MIT License | |
| 290 | Duplicate comments | Find comments that have been registered with a COMMENT statement and that are associated with more than one object. It would probably mean that a comment is incorrect or missing. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2023-03-16 20:33 | MIT License | |
| 291 | Duplicate DEFAULT values of base table columns | Find base table columns that have both default value determined through a domain and default value that is directly attached to the column. Do not duplicate specifications of default values to avoid confusion and surprises. If column and domain both have a default value, then in case of inserting data the default value that is associated directly with the column is used. | Problem detection | INFORMATION_SCHEMA only | 2021-02-25 17:30 | MIT License | |
| 292 | Duplicate domains | Find domains that have the same properties (base type, character length, not null + check constraints, default value). There should not be multiple domains that have the same properties. Do remember that the same task can be solved in SQL usually in multiple different ways. Therefore, the domains may have syntactically different check constraints that solve the same task. Thus, the exact copies are not the only possible duplication. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-02-25 17:30 | MIT License | |
| 293 | Duplicate enumerated types | Find enumerated types with exactly the same values. There should not be multiple types that have the same values. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-02-25 17:30 | MIT License | |
| 294 | Duplicate foreign key constraints | Find duplicate foreign key constraints, which involve the same columns and refer to the same set of columns. | Problem detection | system catalog base tables only | 2021-02-25 17:30 | MIT License | |
| 295 | Duplicate independent (i.e., not created based on a table) composite types | Find composite types with the same attributes (regardless of the order of attributes). Make sure that there is no duplication. | Problem detection | system catalog base tables only | 2021-02-25 17:29 | MIT License | |
| 296 | Duplicate keys | Find completely overlapping key (primary key and unique) constraints. This is a form of duplication. It leads to the creation of multiple indexes to the same set of columns. | Problem detection | system catalog base tables only | 2021-10-16 10:27 | MIT License | |
| 297 | Duplicate materialized views | Find materialized views with exactly the same subquery. There should not be multiple materialized views with the same subquery. Do remember that the same task can be solved in SQL usually in multiple different ways. Thus, the exact copies are not the only possible duplication. | Problem detection | system catalog base tables only | 2021-02-25 17:30 | MIT License | |
| 298 | Duplicate non-fuction based unique indexes | Find pairs of non-function based unique indexes that cover the same set of columns. Include indexes that support a constraint (primary key, unique, exclude), i.e., these indexes have been automatically created due to the constraint declaration. For instance, it helps us to find unique indexes that have been defined to already unique columns. | Problem detection | system catalog base tables only | 2022-10-21 10:17 | MIT License | |
| 299 | Duplicate NOT NULL constraints | Find columns that have NOT NULL constraint through a domain and also directly. Do not duplicate NOT NULL constraints in orde to avoid confusion and surprises. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-02-25 17:30 | MIT License | |
| 300 | Duplicate removal of duplicates in derived tables | Find derived tables (views and materialized views) that contain both DISTINCT and GROUP BY. Make sure that the means for removing duplicate rows from the query result are not duplicated. | Problem detection | INFORMATION_SCHEMA+system catalog base tables | 2021-02-25 17:29 | MIT License | |