типа MEMO в информиксе нет.

Basic Text Search

The Basic Text Search DataBlade® module allows you to search words and phrases in an unstructured document repository stored in a column of a table. The column can be a BLOB, CHAR, CLOB, LVARCHAR, NCHAR, NVARCHAR, or VARCHAR data type. Search strategies include single and multiple character wildcard searches, fuzzy and proximity searches, and AND, OR and NOT Boolean operations. This feature is included with the database server at no extra cost.

Для более сложных поисков надо ставить более мощный Datablade (расширение информикса), например, вот это :

http://www-01.ibm.com/software/data/informix/blades/excaliburtext/