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Subject: Re: Ordering of schema updates and data modifications
References: <EED9649C-95B1-4D7B-80DA-671ADC93D21B@nordsc.com>
From: Colin <colin@clark.ws>
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Message-Id: <1A0661F6-2C62-4867-8CF8-5A1A5C63E43F@clark.ws>
Date: Sun, 18 May 2014 08:29:39 -0500
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
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Hi Jan,

Try waiting a period of time, say 60 seconds, after modifying the schema so t=
he changes propagate throughout the cluster.

Also, you could add a step to your automation where you verify the schema ch=
ange by attempting to insert/delete from the schema with a higher consistenc=
y level to make sure a good number of nodes are in agreement before proceedi=
ng.

Does this make sense?

--
Colin Clark=20
+1-320-221-9531
=20

> On May 18, 2014, at 3:30 AM, Jan Algermissen <jan.algermissen@nordsc.com> w=
rote:
>=20
> Hi,
>=20
> in our project, we apparently have a problem or misunderstanding of the re=
lationship between schema changes and data updates.
>=20
> One team is doing automated tests during build and deployment that execute=
s data migration tests on a development cluster. In those migrations there w=
ill be schema changes (adding rows) and subsequent data insertions involving=
 these rows.
>=20
> It seems, there are unpredictable times when the update reaches the cluste=
r *before* the schema change, causing the tests to fail.
>=20
> What can we do to enforce the schema update to have sufficiently happened b=
efore the modification is hitting the database?
>=20
> Alternatively, what do others do to handle schema migrations during contin=
uous delivery processes.
>=20
> Jan

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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div>Hi Jan,</div><div><br></div><div>Try w=
aiting a period of time, say 60 seconds, after modifying the schema so the c=
hanges propagate throughout the cluster.</div><div><br></div><div>Also, you c=
ould add a step to your automation where you verify the schema change by att=
empting to insert/delete from the schema with a higher consistency level to m=
ake sure a good number of nodes are in agreement before proceeding.</div><di=
v><br></div><div>Does this make sense?<br><br>--<div><div style=3D"margin: 0=
cm 0cm 0.0001pt;"><font style=3D"background-color: rgba(255, 255, 255, 0);">=
<span lang=3D"EN-US"><b>Colin Clark</b>&nbsp;</span><br></font></div></div><=
div style=3D"margin: 0cm 0cm 0.0001pt;"><font style=3D"background-color: rgb=
a(255, 255, 255, 0);"><span lang=3D"EN-US">+1-320-221-9531</span></font></di=
v><div>&nbsp;</div></div><div><br>On May 18, 2014, at 3:30 AM, Jan Algermiss=
en &lt;<a href=3D"mailto:jan.algermissen@nordsc.com">jan.algermissen@nordsc.=
com</a>&gt; wrote:<br><br></div><blockquote type=3D"cite"><div><span>Hi,</sp=
an><br><span></span><br><span>in our project, we apparently have a problem o=
r misunderstanding of the relationship between schema changes and data updat=
es.</span><br><span></span><br><span>One team is doing automated tests durin=
g build and deployment that executes data migration tests on a development c=
luster. In those migrations there will be schema changes (adding rows) and s=
ubsequent data insertions involving these rows.</span><br><span></span><br><=
span>It seems, there are unpredictable times when the update reaches the clu=
ster *before* the schema change, causing the tests to fail.</span><br><span>=
</span><br><span>What can we do to enforce the schema update to have suffici=
ently happened before the modification is hitting the database?</span><br><s=
pan></span><br><span>Alternatively, what do others do to handle schema migra=
tions during continuous delivery processes.</span><br><span></span><br><span=
>Jan</span></div></blockquote></body></html>=

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