PgConf.Russia 2020

Life cycle of Database Migration from Oracle, DB2 to PostgreSQL

Many businesses which use Database management systems like Oracle, DB2 & MS SQL are unreliable these days. Moreover, the costs incurred in maintaining these systems and its product licenses keeps on increasing. As the competitors are migrating over to the new technologies and tools available in the market, it is necessary for these businesses to migrate to new environment which is efficient, consistent and reliable to stay in the market and the technologies used in the current environment have become obsolete or no longer serve the business purpose. PostgreSQL has emerged as a top open-source RDBMS software. Since there is no licensing cost associated with it most of the companies are planning to migrate the databases which are currently running on other RDBMS like Oracle, DB2, MS SQL server to PostgreSQL. This report summarizes the various methodologies, procedures and techniques involved in successfully migrating the data from Oracle to PostgreSQL & DB2 to PostgreSQL. Migration is not a simple effort there should be proper planning and testing involved in this right from database connectivity to performance analysis. In this paper we are going to cover most of the steps which we need to consider before the migration and after the migration like choosing the correct tools for implementing the migration, time taken to migrate ,data compatibility, code conversion, application connectivity to database, database configuration parameters, performance analysis, replication setups, database monitoring, patching and backup strategies.

The performance problems related migrations from PL/SQL to PL/pgSQL

Porting applications from Oracle to Postgres is common work today. Unfortunately it is not without problems. In presentation I'll try to show the basic performance problems related to differences between Oracle and Postgres and PL/SQL and PL/pgSQL.

Non-Relational Postgres

Postgres has always had strong support for relational storage. However, there are many cases where relational storage is either inefficient or overly restrictive. This talk shows the many ways that Postgres has expanded to support non-relational storage, specifically the ability to store and index multiple values, even unrelated ones, in a single database field. Such storage allows for greater efficiency and access simplicity, and can also avoid the negatives of entity-attribute-value (eav) storage. The talk will cover many examples of multiple-value-per-field storage, including arrays, range types, geometry, full text search, xml, json, and records.

Миграция с Oracle на PostgreSQL с использованием автоматического конвертера

В докладе мы хотим рассказать об опыте миграции одной большой системы с Oracle на PostgreSQL. Сама система построена на стеке PHP + Oracle, её отличительной особенностью было то, что вся бизнес-логика была реализована в PL/SQL коде. В СУБД - это более 3000 пакетов с 4-10 функциями (процедурами) в каждом. В PHP - более 10000 форм со вставками анонимных блоков, используемых для получения данных, обработки и сохранения результатов в Oracle.

Для решения этой крайне объемной работы мы взяли ANTLR4 (синтаксический анализатор для чтения, обработки, выполнения или перевода структурированного текста), грамматику PL/SQL и создали автоматический конвертер, который позволяет преобразовать все объекты схемы и нашей системы из Oracle в рабочий код для PostgreSQL.