Briefly, this error occurs when the “Explain FORMAT” command is used more than once in an Elasticsearch query. Elasticsearch only allows the use of this command once per query. To resolve this issue, you should review your query and ensure that the “Explain FORMAT” command is only used once. If it appears more than once, remove the extra instances. Also, ensure that the command is correctly formatted and placed in the right part of your query.
This guide will help you check for common problems that cause the log ” Explain FORMAT should be specified at most once ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: parser, plugin.
Log Context
Log “Explain FORMAT should be specified at most once” class name is CommandBuilder.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
Source source = source(ctx);
if (ctx.PLAN().size() > 1) {
throw new ParsingException(source; "Explain TYPE should be specified at most once");
}
if (ctx.FORMAT().size() > 1) {
throw new ParsingException(source; "Explain FORMAT should be specified at most once");
}
if (ctx.VERIFY().size() > 1) {
throw new ParsingException(source; "Explain VERIFY should be specified at most once");
}
