Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1v9qSd-009TAN-9E for pgsql-admin@arkaria.postgresql.org; Fri, 17 Oct 2025 19:49:58 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1v9qSc-004kVX-64 for pgsql-admin@arkaria.postgresql.org; Fri, 17 Oct 2025 19:49:57 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1v9qSb-004kVP-Ps for pgsql-admin@lists.postgresql.org; Fri, 17 Oct 2025 19:49:56 +0000 Received: from mail-pl1-x630.google.com ([2607:f8b0:4864:20::630]) by magus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.96) (envelope-from ) id 1v9qSY-002m7F-10 for pgsql-admin@lists.postgresql.org; Fri, 17 Oct 2025 19:49:56 +0000 Received: by mail-pl1-x630.google.com with SMTP id d9443c01a7336-28a5b8b12a1so24017575ad.0 for ; Fri, 17 Oct 2025 12:49:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1760730591; x=1761335391; darn=lists.postgresql.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=x9jvIIGG66rTbIIjs5knauc/gwOat7wVd1W0OT03jgc=; b=Hl9As0r0efdnCNwOmcfWDYuBbIbT0O1R6r03jG9Jl4AhmdaeM6NhdLhiVdGdiKzeBH TlOMGLJ4WyL2eUMzirBVwGIIecrGY+mdM1tCGr8hiyfB5+EsEAoIDcR+IARnR/ZxcaSz 9Z7lQLr9dtYA7kjvRQmY7sIZ98i035E+rVnPmibqVyOj4kqlsfKmbn3QhE3XwQi/XPYM 3D8LU0mC0EC8ciQ5o/wXuNpk6HipQY9g2W2BYKUJEC4jyb+RcwbWaXEPsFbJShIb8rV9 t5PU3hYRTNc/SCvSP3+eHrec78KueMxThub3eRHzeGt+7g63OiodfhT1sgoNA2FJX3My JtsQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760730591; x=1761335391; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=x9jvIIGG66rTbIIjs5knauc/gwOat7wVd1W0OT03jgc=; b=Mb9WFgA34C4kluHxJQmgUhkifaRmsrq4AKbgv4bWZtxujsKBDHP4Cs7EOI88TaIvTp YkTugh4DoOFDDbQ6bF6qpE6w/RNF6u1uQM05XzXnVOeTjnaUJwWV10g5X4awYYl7COcr nhr9gEdPXUmxi7hr8yLhD6M1op7Krc81bbhI0rR66RiZyheU4niRFWuIZfai99d+BojT QXXYQnjxwAfYy+cUqJymV8e8PgoxGwRAB7qYiBgouDpQ1qYMO4igzk5s4UPr6nyrMK1K /hwjADqpUUMGaExxTySz20dcN4HYKqT2H/T0cMcYG7Yk1ULQoNS9KeTDNLjEz/W5i0hI coTw== X-Gm-Message-State: AOJu0YzoA8uNaiDvNXpmN1a8IwtnwucttwKggzXCbhlFvSMqclynLRG2 r7iZO/A4M9xWCWnQpdakImoQUEzVk/GEmjpcEG/PeNZqsP2orPCgUxlrtgsemXK7k0NPQbwYFKe x9HxQYqKzFa8MNX/hwrx3GyOHtz/cFho= X-Gm-Gg: ASbGncsn/tkD7e22ehs/OSsJ4KzObw0fmgKTvJTpUUUxd/sGDV7xBGXt0F0lrRGqHk9 f1+3G93l8JlvRVrYuBi7H9HS88xWise1/xx9VDiUTQJVMyRmJAEIZkoKX92xtA9Q777UPFha7c0 8WiKx0RD5O2tp3gVp1bVQD5x+gDmZ5KGIHKPSqPR+gbOogVT40z9yq2CPkqPkZEPc1/WfaipqqW TKugDbARsu2J5GQ+zUrdcAM/lky0BHWkbZyg9zSnRL4r1lqfNUGNuTbXCBn3Dmy+bMUzSuuiYI3 kc/Yr6Q= X-Google-Smtp-Source: AGHT+IGhyyI8G0nf6IuYPGn9oVIFus6IwbuSlgo01mfr7mOjbk6Soj3OjmYGllvYqMwCu9lFLHa18BbWJshsG+1B2Fk= X-Received: by 2002:a17:902:e88e:b0:27e:f018:d312 with SMTP id d9443c01a7336-290c9cf350amr58652865ad.1.1760730591409; Fri, 17 Oct 2025 12:49:51 -0700 (PDT) MIME-Version: 1.0 References: <1915052734.3603827.1760618757611@mail.yahoo.com> In-Reply-To: <1915052734.3603827.1760618757611@mail.yahoo.com> From: mahamood hussain Date: Sat, 18 Oct 2025 01:19:38 +0530 X-Gm-Features: AS18NWDxLkw5HdwdiAgIbrKVXbcNsruJwoAv0Zubj0zWLexgwIpA-OdVxj1GgN4 Message-ID: Subject: Re: Guidance Requested: Migrating Large-Scale DB2 Databases to PostgreSQL To: Brian Crockard Cc: Pgsql-admin Content-Type: multipart/alternative; boundary="0000000000007238870641600955" List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk --0000000000007238870641600955 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Brian, Ron, Kurtoglu, Thank you all for the thoughtful responses. It took a bit of effort to pull this information together, but I'm glad to see the insights coming in =E2= =80=94 it's given me more confidence that this migration is indeed achievable with the right approach. To clarify our setup: We're currently running DB2 LUW v11.5.9 (Advanced Enterprise Server Edition). One of our key concerns is licensing cost, which is driving our move to PostgreSQL. A few follow-up questions based on your responses: 1. InfoSphere Data Replication (CDC): We understand this is a strong option, but it likely incurs additional licensing costs. We=E2=80=99re exploring Fivetran for data replication b= etween DB2 and PostgreSQL, with the flexibility to fall back to DB2 if performance = or stability issues arise in production. - Can CDC be used for such a failback scenario (i.e., from PostgreSQL = =E2=86=92 DB2) similar to how Fivetran supports bidirectional sync? 2. Open-source Tools: Do we have any robust open-source tools that support both forward and backward replication between DB2 and PostgreSQL? This would help us plan for both migration and rollback scenarios without heavy vendor lock-in. 3. Pitfalls to Avoid During Migration: Since our primary goal is cost reduction, we would ideally avoid needing to fall back to DB2. Based on your experience, what are some common pitfalls or gotchas we should look out for when moving from DB2 to PostgreSQL? 4. PostgreSQL Performance Tuning & Config: If there=E2=80=99s a list of standard PostgreSQL parameters that you'd recommend tweaking right after installation =E2=80=94 especially for lar= ge datasets =E2=80=94 that would be very helpful. We're anticipating around 100+ con= current connections during peak hours and migrating some very large tables (up t= o 80B rows). 5. Community vs Enterprise Support: In production, having support with a guaranteed response time (e.g., under an hour) is crucial. - Does the PostgreSQL community offer any premium or paid support options with SLAs, or would we need to go with providers like EDB for this level of assurance? ------------------------------ On Thu, Oct 16, 2025 at 6:15=E2=80=AFPM Brian Crockard wrote: > You may want to look into an IBM product called InfoSphere Data > Replciation (CDC) > > > https://www.ibm.com/docs/nl/idr/11.4.0?topic=3Drequirements-supported-sou= rce-targets > > It will replicate data from DB2 to PostgreSQL. You can set it up to > actively replciate the data and keep it consistent. Then perform a cutove= r > at some point to the new system running against the new replicated > database. You will then have all of your historical data in the new syste= m. > We used this on an extremely active system and it hard very few issues. > > On Wednesday, October 15, 2025 at 05:15:00 PM EDT, mahamood hussain < > hussain.ieg@gmail.com> wrote: > > > Hi Team, > > We are in the process of migrating several DB2 databases to PostgreSQL, > primarily to reduce the high licensing costs associated with DB2. These > databases support retail applications (e.g., supermarkets and stores), an= d > during peak hours, we anticipate over 100 concurrent connections. > ------------------------------ > Current Database Profile: > > - > > Approximately 3,000 tables in total > - > > Around 100 tables contain active data > - > > Most tables have low data volume > - > > A few large tables range from 10 GB to 2 TB > - > > The largest table contains approximately 80 billion rows > > ------------------------------ > Migration Approach: > > - > > We are using Ispirer for code conversion (DB2 to PostgreSQL). > - > > For data migration, we are evaluating Fivetran, but noted that it > relies on the COPY method for data loading. > > ------------------------------ > Questions & Areas Where We Need Guidance: > > 1. > > Is Fivetran a suitable option for migrating very large datasets (e.g., > tables with 80+ billion rows)? > 2. > > Are there any reliable open-source tools for DB2 to PostgreSQL data > migration that we can use internally, without needing to invest in a t= ool > like Fivetran? > 3. > > Are there more scalable or efficient alternatives for both the initial > load and ongoing/incremental sync to PostgreSQL? > > ------------------------------ > Additional Input Requested: > > - > > What are the key best practices (Do=E2=80=99s and Don=E2=80=99ts) to k= eep in mind > during a large-scale DB2 =E2=86=92 PostgreSQL migration? > - > > Are there specific PostgreSQL settings or configurations we should pay > attention to for optimizing performance, especially for large datasets= and > DB2-style workloads? > > ------------------------------ > > We are keen to ensure performance, data integrity, and scalability > throughout this migration. Any insights=E2=80=94particularly from those w= ith > experience in similar large-scale PostgreSQL implementations=E2=80=94woul= d be > highly appreciated. > > If this is not the right forum for these questions, please do let me know > if there is a better place to seek this guidance. > > Thanks in advance for your support! > --0000000000007238870641600955 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

Hi Brian, Ron, Kurtog= lu,

Thank you all for the thoughtful responses. It took a bit of effort to p= ull this information together, but I'm glad to see the insights coming = in =E2=80=94 it's given me more confidence that this migration is indee= d achievable with the right approach.

To clarify our setup:
We're currently running DB2 LUW v11.5.9 (Advanced Enterprise Server Edi= tion). One of our key concerns is licensing cost, which is driving our move= to PostgreSQL.

A few follow-up questions based on y= our responses:

  1. InfoSphere Data Replication (CDC):
    We understand this is a strong option, but it likely incurs additional lice= nsing costs. We=E2=80=99re exploring Fivetran for data replication between = DB2 and PostgreSQL, with the flexibility to fall back to DB2 if performance= or stability issues arise in production.

    • Can CDC be used for such a failback scenario (i.e., from PostgreSQL =E2= =86=92 DB2) similar to how Fivetran supports bidirectional sync?

  2. Open-source Tools:
    Do we have any robust open-source tools =C2=A0that support both forward and= backward replication between DB2 and PostgreSQL? This would help us plan f= or both migration and rollback scenarios without heavy vendor lock-in.

  3. Pitfalls to Avoid During Migration:
    Since our primary goal is cost reduction, we would ideally avoid needing to= fall back to DB2. Based on your experience, what are some common pitfalls = or gotchas we should look out for when moving from DB2 to PostgreSQL?

  4. PostgreSQL Performance Tuning & Config:
    If there=E2=80=99s a list of standard PostgreSQL parameters =C2=A0that you&= #39;d recommend tweaking right after installation =E2=80=94 especially for = large datasets =E2=80=94 that would be very helpful. We're anticipating= around 100+ concurrent connections during peak hours and migrating some ve= ry large tables (up to 80B rows).

  5. Community vs Enterprise Support:
    In production, having support with a guaranteed response time (e.g., under = an hour) is crucial.

    • Does the PostgreSQL community offer any premium or paid support options = with SLAs, or would we need to go with providers like EDB for this level of= assurance?


On Thu, Oct 16, 2025 at 6:15=E2=80=AFPM = Brian Crockard <bcrockard@yahoo.c= om> wrote:
You may want to look into an IBM product called In= foSphere Data Replciation (CDC)



=20
=20


Hi Team,

W= e are in the process of migrating several DB2 databases to PostgreSQL, prim= arily to reduce the high licensing costs associated with DB2. These databas= es support retail applications (e.g., supermarkets and stores), and during = peak hours, we anticipate over 100 concurrent connections.

Current Database Profile:

  • Approximately 3,000 tables in total

  • Around 100 tables contain active data

  • Most tables have low data volume

  • A few large tables range from 10 GB to 2 TB

  • The largest table contains approximately 80 billion rows

Migration Approach:<= /h3>

  • We are using Ispirer for code conversion (DB2 to PostgreSQL).

  • For data migration, we are evaluating Fivetran, but noted that it relies= on the COPY method for data loading.

Questions & Areas Where= We Need Guidance:

  1. Is Fivetran a suitable option for migrating very large datasets (e.g., t= ables with 80+ billion rows)?

  2. Are there any reliable open-source tools for DB2 to PostgreSQL data migr= ation that we can use internally, without needing to invest in a tool like = Fivetran?

  3. Are there more scalable or efficient alternatives for both the initial l= oad and ongoing/incremental sync to PostgreSQL?

Additional Input Requested:=

  • What are the key best practices (Do=E2=80=99s and Don=E2=80=99ts) to kee= p in mind during a large-scale DB2 =E2=86=92 PostgreSQL migration?

  • Are there specific PostgreSQL settings or configurations we should pay a= ttention to for optimizing performance, especially for large datasets and D= B2-style workloads?

We are keen to ensure performance, data integrity, and scalabil= ity throughout this migration. Any insights=E2=80=94particularly from those= with experience in similar large-scale PostgreSQL implementations=E2=80=94= would be highly appreciated.

If this is not the right forum for these= questions, please do let me know if there is a better place to seek this g= uidance.

Thanks in advance for your support!

--0000000000007238870641600955--