ToC path:

mco_translog_query_info

This function reads a specified log file to check it for compatibility with the current database and to enumerate its labels.

For an overview see page TL Applications

Prototype

 
    MCO_RET	mco_translog_query_info (	mco_db_h db, 
                        char const *file_path, 
                        mco_TL_labels_proc labels_proc, 
                        void * user_data, 
                        mco_TL_log_info_h info )

Arguments

db	Database connection handle
file_path	The path and filename or disk partition of the log file.
labels_proc	A user defined call-back function that enumerates labels inside the log file. (Note: May be NULL if is not used).
user_data	A pointer to user-specified data that will be passed to the call-back function `labels_proc`.
info	A pointer to a structure defined as: typedef struct mco_TL_log_info_ { mco_trans_counter_t start_trans_counter; mco_trans_counter_t stop_trans_counter; mco_trans_counter_t stored_transactions; uint2 disk_page_size; uint2 page_size; mco_size_t log_size; int labels_count; mco_bool crc; mco_bool aligned; mco_bool dictionary_compat; mco_bool transaction_apply_compat; mco_bool transaction_append_compat; mco_bool not_corrupted; mco_bool iteratable; } mco_TL_log_info_t,*mco_TL_log_info_h; Note: May be NULL if is not used (i.e. is used only to enumerate the labels). (The structure elements are explained below.)

Description

This function reads a specified log file to check it for compatibility with the current database and to enumerate its labels.

Return Codes

MCO_S_OK	The TL runtime was initialized successfully.
MCO_E_TL_LOG_NOT_OPENED	The log file could not be opened.
MCO_E_TL_IO_ERROR	Disk IO error.
MCO_E_VERS_MISMATCH	The log file is incompatible with the runtime settings or the database version.
MCO_E_TL_INVFORMAT	The log file is corrupted.
MCO_S_TL_INVDATA	The log file was not read completely but some transactions were found or no end-of-file was found. In the latter case `info.transaction_apply_compat` will be `MCO_YES`, info.not_corrupted will be `MCO_NO` and `info.transaction_append_compat` will be `MCO_NO`.

The structure elements for structure mco_TL_log_info are defined as follows:

start_trans_counter	The value of the transaction counter when the log file was started.
last_trans_counter	The value of the transaction counter when the log file was finished.
stored_transactions	The count of transactions stored in the log file.
disk_page_size	Size of a single disk page.
page_size	Size of an in-memory database page.
log_size	The total size of the log file, in bytes.
labels_count	The count of labels stored in the log file.
crc	`MCO_YES` if the log was created with `MCO_TRANSLOG_CRC` flag; otherwise `MCO_NO`.
aligned	`MCO_YES` if the log was created with `MCO_TRANSLOG_ALIGNED` flag; otherwise `MCO_NO`.
dictionary_compat	`MCO_YES` if the log file is compatible with the database specified by the argument "db"; otherwise `MCO_NO`.
transaction_apply_compat	`MCO_YES` if the log file is compatible for applying to the database specified by argument "db" (by transaction number); otherwise `MCO_NO`.
transaction_append_compat	`MCO_YES` if the log file is compatible for appending to the database specified by argument "db" (by transaction number); otherwise `MCO_NO`.
not_corrupted	`MCO_YES` if no data has been lost since the last save-point.
iteratable	`MCO_YES` if the log file was written with the `MCO_TRANSLOG_ITERABLE` flag.

The user-defined callback procedure labels_proc must have the following prototype:

 
    typedef void(*mco_TL_labels_proc)(const char *label, int label_id, void *data);

where label is the label text, label_id is the integer value associated with this label (that was generated by the TL runtime when the function mco_translog_label() was called), and data is a pointer to application-specific data that may be used in the implementation of the label procedure.

Files

Header file:

mcolog.h

Source file:

mcolog.c

Library:

libmcolog.a