pg4n package
Submodules
pg4n.cmp_domain_checker module
- class pg4n.cmp_domain_checker.CmpContext(expression, a, b)[source]
Bases:
object- expression: Predicate
pg4n.config_parser module
- class pg4n.config_parser.ConfigParser(file)[source]
Bases:
object- parse()[source]
Reads config values from file givein in __init__.
- Return type
Optional[ConfigValues]
pg4n.config_reader module
- class pg4n.config_reader.ConfigReader[source]
Bases:
object- read()[source]
The configuration files are read in order from: /etc/pg4n.conf then from $XDG_CONFIG_HOME/pg4n.conf, or if $XDG_CONFIG_HOME is not set, from $HOME/.config/pg4n.conf, and lastly from $PWD/pg4n.conf, with each new value introduced in latter files overriding the previous value.
- Return type
Optional[ConfigValues]
pg4n.config_values module
pg4n.eq_wildcard_checker module
pg4n.errfmt module
pg4n.implied_expression_checker module
pg4n.inconsistent_expression_checker module
- class pg4n.inconsistent_expression_checker.InconsistentExpressionChecker(parsed_sql, qep_analysis)[source]
Bases:
objectInconsistent expression is some expression that is never true. For example: x = 10 AND x = 20
This checker only finds a small subset of such expression, where postgresql itself detects the inconsistent expression in its query optimizer and exposes that information via its query execution plan.
pg4n.main module
pg4n.psqlconninfo module
- class pg4n.psqlconninfo.PsqlConnInfo(psql_args)[source]
Bases:
objectGet PostgreSQL server address, port, database name, and user via psql by supplying same arguments as the original psql process. This way we can avoid writing a command-line argument parser.
- get()[source]
Get 5-tuple that has the PostgreSQL host, port, user, pass, and db name.
- Returns
Optional[Tuple[str,str,str,str,str]] – (hostname, port, user, password, database name) 5-tuple or None.
- tok_database(name=None): ParserElement = W:(0-9A-Z_a-zªµ·...)
- tok_end(name=None): ParserElement = '".'
- tok_host(name=None): ParserElement = W:(.-9A-Z_a-zªµ·...)
- tok_port(name=None): ParserElement = W:(0-9)
- tok_pre_database(name=None): ParserElement = 'You are connected to database "'
- tok_pre_host(name=None): ParserElement = {'" on host "' | '" via socket in "'}
- tok_pre_port(name=None): ParserElement = '" at port "'
- tok_pre_user(name=None): ParserElement = '" as user "'
- tok_user(name=None): ParserElement = W:(0-9A-Z_a-zªµ·...)
pg4n.psqlparser module
Parse psql output.
- class pg4n.psqlparser.PsqlParser[source]
Bases:
objectParses psql output for syntactic analysis.
- debug: bool = False
- multiline_prompt_ends: list[str] = ['-#', '*#', "'#", '"#', '$#', '(#', '->', '*>', "'>", '">', '$>', '(>', '-*#', '**#', "'*#", '"*#', '$*#', '(*#', '-*>', '**>', "'*>", '"*>', '$*>', '(*>', '-!#', '*!#', "'!#", '"!#', '$!#', '(!#', '-!>', '*!>', "'!>", '"!>', '$!>', '(!>', '-?#', '*?#', "'?#", '"?#', '$?#', '(?#', '-?>', '*?>', "'?>", '"?>', '$?>', '(?>']
- output_has_magical_return(psql)[source]
Check for weird Return presses.
- Parameters
psql (
str) – Raw console output that includes terminal control codes.- Returns
bool– if output has a weird Return press.
- output_has_new_prompt(psql)[source]
Detect when psql query evaluation has ended by parsing for a new prompt.
- Parameters
psql (
str) – Raw console output that includes terminal control codes.- Returns
bool– if output is a fresh prompt.
- parse_last_stmt(psql)[source]
Parse for last SQL query statement in a string.
- Parameters
psql (
str) – screenscraped psql string with only whitespace after most recent query.- Returns
str– parsed SQL query as plain string.
- parse_new_prompt_and_rest(psql)[source]
Parse for a fresh prompt and everything preceding it into 2-length list, facilitating easy message injection.
- Parameters
psql (
str) – Raw console output that includes terminal control codes.- Returns
list[str] – a two-part list with everything before the prompt line and then the prompt, to allow easy message injection.
List is empty if no fresh prompt was found.
- parse_psql_version(psql)[source]
Parse for psql version and return version number.
- Parameters
psql (
str) – psql –version output- Returns
str– version string (e.g “14.5”)
- parse_syntax_error(psql)[source]
Parse for syntax error output.
- Parameters
psql (
str) – screen-scraped psql output.- Returns
str– syntax error message from ‘ERROR:’ to last ‘^’.
- prompt_chars: str = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyzªµ·ºÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓÔÕÖØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ'
- stmt_chars: str = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!"#$%&\'()*+,-./:<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c'
- stmt_end: str = ';'
- tok_rev_prompt_end(name=None): ParserElement = Combine:({{[<SP><TAB><CR><LF>] {'#' | '>'}} [{'*' | '!'} | '?']} {'=' | '^'})
pg4n.psqlwrapper module
Interface with psql and capture all input and output.
Uses pexpect in combination with pyte for interfacing and screen-scraping respectively.
- class pg4n.psqlwrapper.PsqlWrapper(psql_args, hook_semantic_f, hook_syntax_f, parser)[source]
Bases:
objectHandles terminal interfacing with psql, using the parameter parser to pick up relevant SQL statements and syntax errors for hook functions.
- debug: bool = False
- start()[source]
Start psql process and feed hook functions with intercepted queries and syntax errors.
Control is only returned after psql process exits.
- Return type
None
- supported_psql_versions: list[str] = ['14.5']
pg4n.qepparser module
- class pg4n.qepparser.QEPAnalysis(qep_)[source]
Bases:
objectRepresents the result of EXPLAIN ANALYZE.
- property plan: Plan
A dict of the root node’s properties.
- Return type
Plan
- property qep: QEP
A dict of the query execution plan’s properties.
- Return type
QEP
- class pg4n.qepparser.QEPNode(node_)[source]
Bases:
objectA node in a query execution plan.
- find(pr, recursive=False)[source]
Finds nodes matching the predicate.
- Parameters
pr (
Callable[[Plan],bool]) – a function that takes a node and returns True if it matchesrecursive – if True, search recursively, otherwise only search this+children
- Returns
list[Plan] – a list of matching nodes
- findval(key, val, recursive=False)[source]
Finds nodes with the given key and value.
- Parameters
key (
str) – the key to search forval (
object) – the value to search forrecursive – if True, search recursively, otherwise only search this+children
- Returns
list[Plan] – a list of matching nodes
- property plan: Plan
A dict of the node’s properties.
- Return type
Plan
- property plans: list[pg4n.qepparser.Plan]
A list of the node’s children.
- Return type
list[Plan]
- class pg4n.qepparser.QEPParser(*args, conn=None, constraint_exclusion=True, **kwargs)[source]
Bases:
objectPerforms analyses on given queries, returning resultant QEPAnalysis.
- pg4n.qepparser.node
alias of
Plan
- pg4n.qepparser.qep
alias of
QEP
pg4n.semanticrouter module
Handle semantic analysis modules.
- class pg4n.semanticrouter.SemanticRouter(pg_host, pg_port, pg_user, pg_pass, pg_name, config_values)[source]
Bases:
objectAnalyze given SQL queries via a plethora of analysis modules.
- run_analysis(sql_query)[source]
Run analysis modules on SQL query string and get an insightful message in return.
Semantic router (some day) implements basic heuristics to avoid running all the modules on all queries. For now, it is dumb brute force router. :type sql_query:
str:param sql_query: is a single well-formed query to run analytics on. :return:str– an insightful message that might include vt100-compatible control codes and newlines (without carriage returns).
pg4n.sqlparser module
- class pg4n.sqlparser.Column(name, type, table)[source]
Bases:
object- name: str
- table: str
- type: PostgreSQLDataType
- class pg4n.sqlparser.PostgreSQLDataType(name, digits, precision)[source]
Bases:
object- digits: Optional[int]
- name: str
- precision: Optional[int]
- class pg4n.sqlparser.SqlParser(db_connection)[source]
Bases:
object- static find_all_table_names(parsed_sql)[source]
Finds all unique table names in ‘parsed_sql’. Any table name with an alias is listed without the alias (e.g.: FROM <table> AS <alias>) Also removes duplicate table names from the result.
- Return type
list[str]
- static find_where_predicates(root)[source]
Finds all Predicate nodes inside Where statements from some root node (usually the whole parsed output from sqlparser.parse_one()). This function takes care to not introduce any duplicate Predicate’s in case of nested Where statements.
- Return type
list[Predicate]
- static get_column_name_from_column_expression(column_expression)[source]
Returns the column name of column expression ast node.
- Return type
str
- get_query_columns(parsed_sql)[source]
Gets all columns from all tables mentioned in parsed_sql.
- Return type
list[Column]
- static get_root_node(node)[source]
Finds the root node (probably exp.Select) from node.
- Return type
Expression