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Cannot prepare query longer than 73707 characters. #2635

catsaremine opened this issue Sep 24, 2019 · 0 comments


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commented Sep 24, 2019

Steps to reproduce

using System;
using System.Threading.Tasks;
using Npgsql;

namespace PgBlobParam
    class Program
        static async Task Main(string[] args)
            const string connectionString = "xxxx";
            int queryLength = 73708;

            string template = "select '{0}';";

            string sql = string.Format(template, new string('A', (queryLength - template.Length) + 3)); // +3 for the '{0}'.

            using (var connection = new NpgsqlConnection(connectionString))
                await connection.OpenAsync();

                    using (var command = connection.CreateCommand())
                        command.CommandText = sql;

                        await command.PrepareAsync();

                        await command.ExecuteNonQueryAsync();

                catch (Exception e)


The issue

When you have a query that is longer than 73707 characters the driver fails and throws an exception: Received backend message ParseComplete while expecting ReadyForQueryMessage. Please file a bug.

Exception message: Received backend message ParseComplete while expecting ReadyForQueryMessage. Please file a bug.

Stack trace:
  at Npgsql.NpgsqlCommand.<>c__DisplayClass74_0.<<Prepare>g__PrepareLong|0>d.MoveNext()
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at PgBlobParam.Program.<Main>d__0.MoveNext() in D:\Dev\small-projects\PgBlobParam\Program.cs:line 33

Further technical details

Npgsql version: 4.0.10
PostgreSQL version: psql (PostgreSQL) 11.5 (Ubuntu 11.5-1.pgdg16.04+1)
Operating system: Ubuntu 16.04

@roji roji added the bug label Sep 24, 2019
@roji roji added this to the 4.0.11 milestone Sep 24, 2019
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