Documentation
¶
Overview ¶
Package postgres provides PostgreSQL-specific schema comparison engine.
Overview ¶
This package implements the ComparisonEngine interface for PostgreSQL databases, handling PostgreSQL-specific features and comparison logic.
PostgreSQL-Specific Features ¶
The PostgreSQL engine handles:
- Schemas (namespaces)
- Extensions (PostGIS, pg_trgm, etc.)
- Sequences and IDENTITY columns
- Enum types
- Materialized views
- GIN, GIST, BRIN, and other specialized indexes
- Partial indexes (WHERE clauses)
- Expression indexes
- Rules (rewrite rules)
- Foreign data wrappers (future)
Type Comparison ¶
PostgreSQL has rich type system with specific comparison rules:
- VARCHAR vs TEXT vs CHARACTER VARYING
- SERIAL vs INTEGER with sequence
- Array types (e.g., INTEGER[])
- Domain types
- Custom composite types
The engine normalizes types and handles type aliases to detect true semantic changes.
Schema Awareness ¶
PostgreSQL supports multiple schemas (namespaces) within a database. The engine properly handles qualified names (schema.table) and compares objects within their schema context.
Expression Handling ¶
PostgreSQL expressions require special handling:
- Type casts (::type vs CAST)
- Function overloading
- Operator precedence
- Array and JSON operators
Compatibility ¶
Supports PostgreSQL 10+ including newer features like declarative partitioning, logical replication objects, and stored procedures (vs functions).
Index ¶
- type ColumnComparer
- type Comparer
- type ExpressionComparer
- type FunctionComparer
- func (c *FunctionComparer) CanUseAlterFunction(oldFunc, newFunc *schemaextract.Function) bool
- func (c *FunctionComparer) CompareDetailed(oldFunc, newFunc *schemaextract.Function) (*diff.FunctionComparisonResult, error)
- func (c *FunctionComparer) Equal(oldFunc, newFunc *schemaextract.Function) bool
- func (c *FunctionComparer) GetSignature(function *schemaextract.Function) string
- type ViewComparer
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ColumnComparer ¶
type ColumnComparer struct {
*defaultcomparer.BaseColumnComparer
}
ColumnComparer implements PostgreSQL-specific column comparison.
func NewColumnComparer ¶
func NewColumnComparer() *ColumnComparer
NewColumnComparer creates a new PostgreSQL column comparer.
func (*ColumnComparer) CompareColumns ¶
func (c *ColumnComparer) CompareColumns(oldCol, newCol *schemaextract.Column) (*diff.ColumnDiff, error)
CompareColumns compares two PostgreSQL columns.
func (*ColumnComparer) IsEquivalentType ¶
func (c *ColumnComparer) IsEquivalentType(type1, type2 string) bool
IsEquivalentType checks if two PostgreSQL types are semantically equivalent. Examples:
- INTEGER = INT = INT4
- CHARACTER VARYING = VARCHAR
- TIMESTAMP WITH TIME ZONE = TIMESTAMPTZ
func (*ColumnComparer) NormalizeType ¶
func (c *ColumnComparer) NormalizeType(colType string) string
NormalizeType normalizes a PostgreSQL column type.
type Comparer ¶
type Comparer struct {
*defaultcomparer.BaseComparer
// contains filtered or unexported fields
}
Comparer implements PostgreSQL-specific schema comparison.
func (*Comparer) Column ¶
func (c *Comparer) Column() engine.ColumnComparer
Column returns the PostgreSQL column comparer.
func (*Comparer) Expression ¶
func (c *Comparer) Expression() engine.ExpressionComparer
Expression returns the PostgreSQL expression comparer.
func (*Comparer) Function ¶
func (c *Comparer) Function() engine.FunctionComparer
Function returns the PostgreSQL function comparer.
func (*Comparer) View ¶
func (c *Comparer) View() engine.ViewComparer
View returns the PostgreSQL view comparer.
type ExpressionComparer ¶
type ExpressionComparer struct {
engine.ExpressionComparer
}
ExpressionComparer implements PostgreSQL-specific expression comparison.
func NewExpressionComparer ¶
func NewExpressionComparer() *ExpressionComparer
NewExpressionComparer creates a new PostgreSQL expression comparer.
func (*ExpressionComparer) CompareExpressionsSemantically ¶
func (c *ExpressionComparer) CompareExpressionsSemantically(expr1, expr2 string) (bool, error)
CompareExpressionsSemantically compares two PostgreSQL expressions semantically. It normalizes both expressions and uses the parser to compare their ASTs.
func (*ExpressionComparer) IsEquivalentExpression ¶
func (c *ExpressionComparer) IsEquivalentExpression(expr1, expr2 string) bool
IsEquivalentExpression checks if two expressions are semantically equivalent using PostgreSQL-specific rules.
func (*ExpressionComparer) NormalizeExpression ¶
func (c *ExpressionComparer) NormalizeExpression(expr string) string
NormalizeExpression normalizes a PostgreSQL expression. This handles PostgreSQL-specific quirks: - IN (...) to ANY(ARRAY[...]) equivalence - Interval syntax variations - Type cast removal (::type) - Extra parentheses
type FunctionComparer ¶
type FunctionComparer struct {
*defaultcomparer.BaseFunctionComparer
// contains filtered or unexported fields
}
FunctionComparer implements PostgreSQL-specific function comparison.
func NewFunctionComparer ¶
func NewFunctionComparer() *FunctionComparer
NewFunctionComparer creates a new PostgreSQL function comparer.
func (*FunctionComparer) CanUseAlterFunction ¶
func (c *FunctionComparer) CanUseAlterFunction(oldFunc, newFunc *schemaextract.Function) bool
CanUseAlterFunction determines if ALTER FUNCTION can be used. PostgreSQL allows ALTER FUNCTION for body changes.
func (*FunctionComparer) CompareDetailed ¶
func (c *FunctionComparer) CompareDetailed(oldFunc, newFunc *schemaextract.Function) (*diff.FunctionComparisonResult, error)
CompareDetailed provides detailed comparison with PostgreSQL-specific logic.
func (*FunctionComparer) Equal ¶
func (c *FunctionComparer) Equal(oldFunc, newFunc *schemaextract.Function) bool
Equal checks if two functions are identical, using semantic comparison for definitions.
func (*FunctionComparer) GetSignature ¶
func (c *FunctionComparer) GetSignature(function *schemaextract.Function) string
GetSignature extracts function signature (name + parameter types).
type ViewComparer ¶
type ViewComparer struct {
*defaultcomparer.BaseViewComparer
// contains filtered or unexported fields
}
ViewComparer implements PostgreSQL-specific view comparison.
func NewViewComparer ¶
func NewViewComparer() *ViewComparer
NewViewComparer creates a new PostgreSQL view comparer.
func (*ViewComparer) CompareView ¶
func (c *ViewComparer) CompareView(oldView, newView *schemaextract.View) (*diff.ViewComparisonResult, error)
CompareView compares two views with semantic comparison.
Source Files